1 2 3 47 6 Journal of Integer Sequences, Vol. 18 (2015), Article 15.10.5 23 11 Generalized Anti-Waring Numbers Chris Fuller and Robert H. Nichols, Jr. Labry School of Science, Technology, and Business Cumberland University 1 Cumberland Square Lebanon, TN 37087 USA cfuller@cumberland.edu rnichols@cumberland.edu Abstract The anti-Waring problem considers the smallest positive integer such that it and every subsequent integer can be expressed as the sum of the k th powers of r or more distinct natural numbers. We give a generalization that allows elements from any nondecreasing sequence, rather than only the natural numbers. This generalization is an extension of the anti-Waring problem, as well as the idea of complete sequences. We present new anti-Waring and generalized anti-Waring numbers, as well as a result to verify computationally when a generalized anti-Waring number has been found. 1 Introduction For positive integers k and r, the anti-Waring number N (k, r) is defined to be the smallest positive integer such that N (k, r) and every subsequent positive integer can be expressed as the sum of the k th powers of r or more distinct positive integers. Several authors [3, 5, 7, 11] recently reported results on anti-Waring numbers. Early results considered only r = 1. As early as 1948, Sprague found that N (2, 1) = 129 [15] and proved that N (k, 1) exists for all k ≥ 2 [16]. In 1964, Graham [6] reported that N (3, 1) = 12759 (Graham [6] references another Graham paper “On the Threshold of completeness for certain sequences of polynomial values” said to appear circa 1964). Dressler and Parker [4] also computed N (3, 1) in 1974. Lin [10] used Graham’s method to find that 1 N (4, 1) = 5134241 with a computer in 1970. In 1992, Patterson [12, pp. 18–23] found that N (5, 1) = 67898772. In this paper, we independently verify each of these numbers and show that N (6, 1) = 11146309948. More recently, Looper and Saritzky [11] proved that N (k, r) exists for all positive integers k and r. Deering and Jamieson [3] found specific values of N (2, r) for 1 ≤ r ≤ 10 and N (3, r) for 1 ≤ r ≤ 5. Shortly afterwards, Fuller et al. [5] computed values of N (2, r) for 1 ≤ r ≤ 50 and N (3, r) for 1 ≤ r ≤ 30. We also verify these numbers and present N (k, r) for more values of k and r. One can verify a suspected value of N (k, r) using different sets of conditions [3, 5]. In an effort to generalize the anti-Waring results we consider a nondecreasing sequence of positive integers A = (ai )i∈N . Here and throughout we use N = {1, 2, 3, . . . }. For positive integers k, n, and r we define the generalized anti-Waring number N (k, n, r, A) to be the smallest positive integer, if it exists, such that it and every subsequent positive integer can be expressed as the sum of the k th powers of the ai with i ≥ n ranging over r or more distinct values. If the sequence A has all distinct elements, we may use set notation for the last argument of the generalized anti-Waring number. The generalized anti-Waring number N (k, n, r, A) does not exist for all sequences A (see Theorems 1 and 2 in Section 2). Looper and Saritzky [11] proved that both the anti-Waring number N (k, r) and the generalized anti-Waring number N (k, n, r, N) exist for all positive integers k, n, and r. Early results of these generalized anti-Waring numbers when restricting r to 1 used different terminology. A nondecreasing sequence S of positive integers is complete if all sufficiently large positive integers can be written as a sum of distinct elements of S. If S is a complete sequence, the threshold of completeness, θ(S), is the largest positive integer that is not expressible as a sum of distinct elements of S. Therefore, the threshold of completeness, θ(S), is one less than the generalized anti-Waring number N (1, 1, 1, S). Also, if S = (si )i∈N is a nondecreasing sequence of positive integers such that the sequence (ski )i≥n is complete, then the generalized anti-Waring number N (k, n, 1, S) exists and N (k, n, 1, S) − 1 = θ (ski )i≥n . Brown [1] defined a sequence to be complete only when the threshold of completeness is zero; we use the more general definition. In the literature on complete sequences, some authors only report that a sequence is complete and hence the generalized anti-Waring number exists; some authors actually find the threshold of completeness. In 1952, Lekkerkerker [9] reported an account of the Zeckendorf representation (circa 1939 [17]), i.e., that every natural number is either a Fibonacci number or can be expressed as the sum of nonconsecutive Fibonacci numbers. Hence the generalized anti-Waring number for the Fibonacci sequence F is N (1, 1, 1, F ) = 1. In 1975, Kløve [8] found thresholds of completeness for sequences of the form (⌊iα ⌋)i∈N , where ⌊x⌋ is the floor function, for 1 ≤ α ≤ 4.18 in increments of 0.02. In 1978, Porubský [13] proved that N (k, 1, 1, P) exists for all positive integers k and the sequence of primes P. Burr and Erdős [2] considered perturbations of complete sequences that resulted in noncomplete sequences and vice versa. Generalized anti-Waring numbers extend the concept of anti-Waring numbers to sequences other than N. The generalization also extends the concept of complete sequences 2 to consider sums of r or more terms. We will present conditions needed to verify values of N (k, n, r, A) computationally, sequences for which no N (k, n, r, A) exists, and new values of N (k, n, r, A) for various sequences. 2 Verifying N (k, n, r, A), when it exists For given positive integers k, n, r, and any nondecreasing sequence of positive integers A = (ai )i∈N , we define a positive integer to be (k, n, r, A)-good if it can be written as a sum of the k th powers of r or more distinct elements of the sequence (ai )i≥n . We define a positive integer that is not (k, n, r, A)-good to be (k, n, r, A)-bad. Hence the generalized anti-Waring number N (k, n, r, A) is the smallest positive integer such that it and every subsequent integer is (k, n, r, A)-good. Equivalently the threshold of completeness N (k, n, r, A) − 1 is the largest integer that is (k, n, r, A)-bad. The generalized anti-Waring number N (k, n, r, A) does not exist for all sequences A. For example, the sum of any elements of the sequence (2, 4, 6, 8, . . .) of positive even integers will never be odd. This is an instance of a more general phenomenon. Theorem 1. Let A = (ai )i∈N be a nondecreasing sequence of positive integers. If all ai for i ≥ n have a common divisor d > 1, then for any positive integers k and r, the generalized anti-Waring number N (k, n, r, A) does not exist. Proof. Every sum of positive powers of the ai , i ≥ n, is divisible by d. Since d > 1, arbitrarily large integers not divisible by d exist. Thus, arbitrarily large integers not representable in any way as a sum of powers of some of the an , an+1 , . . . also exist. If instead the greatest common divisor is one, then the generalized anti-Waring number may or may not exist. We will consider examples of both cases. As an additional example, the sequence of factorials has no generalized anti-Waring number. Theorem 2. Let A = (i!)i∈N , and let k, n, and r are any positive integers. Then the generalized anti-Waring number N (k, n, r, A) does not exist. Proof. First notice that for each ai ∈ A, if i = 1; 1, k k ai mod 6 ≡ 2 mod 6, if i = 2; 0, if i > 2. Consider any (k, n, r, A)-good number m. Distinct integers i1 , i2 , . . . , it exist such that m = aki1 + aki2 + · · · + akit where t ≥ r and iα ≥ n for each α ∈ {1, 2, . . . , t}. Thus the sum m must be 0, 1, 2k , or 1 + 2k modulo 6. Since we can have at most four consecutive (k, n, r, A)-good integers, no largest (k, n, r, A)-bad integer exists. 3 On the other hand, in some cases the generalized anti-Waring number N (k, n, r, A) is known to exist, but its value has not been found. As mentioned above, both the anti-Waring number N (k, r) and the generalized anti-Waring number N (k, n, r, N) exist for all k, n, and r [11]. A general formula for either of these is not known, but we present several values in the next section. We rewrite the following result related to complete sequences by Brown [1, Theorem 1] in terms of generalized anti-Waring numbers. Theorem 3. Let k and n be positive integers, and let A = (ai )i∈N be a nondecreasing sequence of positive integers. The generalized anti-Waring number N (k, n, 1, A) both and equals Pp exists k k one if and only if (i) an = 1 and (ii) for all integers p ≥ n, ap+1 ≤ 1 + i=n ai . This result only considers r = 1. Also since Brown [1] defined complete sequences requiring the threshold of completeness to be zero, he requires an = 1. Theorem 3 proves that all positive integers are representable as a sum of different elements of sequences such as the natural numbers, the Fibonacci numbers, and the powers of two (including 20 ). We must consider different conditions for the more general definition of complete sequences with any threshold of completeness. The next result from Graham [6, Theorem 4] establishes completeness conditions for sequences generated by polynomials. Theorem 4. Let f (x) be a polynomial with real coefficients expressed in the form x x f (x) = α0 + α1 + · · · + αn , αn 6= 0. 1 n The sequence S(f ) = (f (1), f (2), · · · ) is complete if and only if 1. αk = pk /qk for some integers pk and qk with gcd(pk , qk ) = 1 and qk 6= 0 for 0 ≤ k ≤ n, 2. αn > 0, and 3. gcd(p0 , p1 , . . . , pn ) = 1. Again, in terms of generalized anti-Waring numbers Theorem 4 only considers the case of r = 1 and can only be used to establish that a given generalized anti-Waring number exists. As a remark to this theorem, Graham notes that a sequence (f (1), f (2), f (3), . . .) is complete if and only if (f (n), f (n + 1), f (n + 2), . . .) is complete for any n. The next theorem shows that nothing like this can be expected in general. Theorem 5. Let k, n, and r be positive integers, and let A be a sequence of nondecreasing positive integers. If the generalized anti-Waring number N (k, n, r, A) exists, then so does N (k, j, r, A) for j ∈ {1, 2, . . . , n − 1} and N (k, j, r, A) ≤ N (k, n, r, A). Furthermore, the converse is false. 4 Proof. The implication is clear. If all positive integers greater than or equal to N (k, n, r, A) can be written as a sum k th powers of r or more distinct elements of (ai )i≥n , then, with the same elements, each positive integer can be written as a sum k th powers of r or more distinct elements of (ai )i≥j for j ∈ {1, 2, . . . , n − 1}. Therefore, we have N (k, j, r, A) ≤ N (k, n, r, A) for j ∈ {1, 2, . . . , n − 1}. To see that the converse is false, consider the sequence A = (2i−1 )i∈N . From the binary representation of the positive integers, the generalized anti-Waring number N (1, 1, 1, A) clearly exists and equals one. However, the generalized anti-Waring number N (1, 2, 1, A) does not exist because no odd integer can be expressed as a sum of elements from (2i−1 )i≥2 . In general, whether N (k, n, r, A) exists or not cannot easily be determined. However, we can validate a suspect value of N (k, n, r, A) if enough consecutive integers are (k, n, r, A)good and certain other conditions are met. Theorem 6 is a generalization of a recent result for anti-Waring numbers [5, Theorem 2.2]. Theorem 6. Let k, n, r, b, and N̂ be positive integers, and let A = (ai )i∈N with 0 < ai ≤ ai+1 and ai ∈ N for all i. If the consecutive integers {N̂ , . . . , bk } are all (k, n, r, A)-good, the number N̂ − 1 is (k, n, r, A)-bad, and there exists a positive integer x such that the conditions 1. N̂ ≤ bk + 1 − (b − x)k , 2. an ≤ b − x, 3. 0 < n+r−2 X i=n aki ! + 2(m − x)k − (m + 1)k for all m ≥ b, and 4. (m + 1)k − (m − x)k ≤ mk for all m ≥ b hold, then the generalized anti-Waring number N (k, n, r, A) exists and equals N̂ . Note: The sum in condition 3 is zero if r = 1. Proof. We want to prove that if ℓ ≤ mk and ℓ is (k, n, r, A)-bad, then ℓ ≤ N̂ − 1 by induction on m with m ≥ b. This is clearly true for m = b as we know the consecutive integers {N̂ , . . . , bk } are all (k, n, r, A)-good. Now suppose ℓ ≤ (m+1)k and ℓ is (k, n, r, A)-bad. If ℓ ≤ mk , then by induction ℓ ≤ N̂ −1. Next, consider ℓ such that mk + 1 ≤ ℓ ≤ (m + 1)k . (1) Notice bk − (b − x)k ≤ mk − (m − x)k for m ≥ b. Using this along with (1) and condition 1, we have N̂ ≤ ℓ − (m − x)k . (2) To see that ℓ − (m − x)k is (k, n, r, A)-bad, suppose it is (k, n, r, A)-good. Then ℓ − (m − x)k = aki1 + aki2 + aki3 + · · · + akit 5 where t ≥ r, iα 6= iβ for all α 6= β, and iα ≥ n for all α ∈ {1, 2, . . . , t}. Since ℓ is (k, n, r, A)bad and ℓ = aki1 + aki2 + aki3 + · · · + akit + (m − x)k , either m − x < an , which contradicts condition 2, or aiα = m − x for some α ∈ {1, 2, . . . , t}. Therefore, ℓ ≥ akn + akn+1 + akn+2 + · · · + akn+r−2 + 2(m − x)k . If r = 1, this is just ℓ ≥ 2(m − x)k . Combining with (1), we get ! n+r−2 X aki + 2(m − x)k − (m + 1)k ≤ 0. i=n This contradicts condition 3 and means that ℓ − (m − x)k must be (k, n, r, A)-bad. Now from (1) and condition 4, ℓ − (m − x)k ≤ (m + 1)k − (m − x)k ≤ mk . By induction we then have ℓ − (m − x)k ≤ N̂ − 1. This contradicts (2). Hence there are no ℓ that are (k, n, r, A)-bad and satisfy (1). Most of the threshold of completeness results in the literature of complete sequences rely on work by Richert [14], where different sufficient conditions imply that a sequence is complete when restricting r = 1. Our algorithms for computing generalized anti-Waring numbers were designed to stop when x and b are found satisfying Theorem 6. 3 Values of N (k, n, r, A) As a result of Theorems 1 and 2, we know that N (k, n, r, A) does not exist for all values of k, n, and r and all sequences A. Ideally, if the generalized anti-Waring number N (k, n, r, A) exists, a formula for it can be derived. We have found such a formula for some cases. For other cases, we have computationally found and verified N (k, n, r, A) with Theorem 6. Johnson and Laughlin [7, Theorem 1] proved a first result N (1, 1, r, N) = r X i=1 r i = (r + 1) 2 (3) for the case of k = n = 1. A similar argument is valid for general values of n. Theorem 7. For positive integers n and r, the generalized anti-Waring number is given by N (1, n, r, N) = n+r−1 X i=n r i = (r + 1) + r(n − 1). 2 6 P Proof. Clearly, the sum n+r−1 i is the smallest integer expressible as the sum of r or more i=n distinct integers greater than or equal to n. For any positive integer x greater than the sum Pn+r−1 i, we have i=n n+r−2 X x− i > n + r − 1. i=n Finally, we have that x= n+r−2 X i+ x− i=n n+r−2 X i=n i ! so the integer x is the sum of r distinct integers greater than or equal to n. Theorem 8. For positive integers n, r, and s and integers t such that |t| < s and gcd(s, t) = 1, the generalized anti-Waring number is given by N (1, n, r, (si + t)i∈N ) = 1 − s + n+r+s−2 X (si + t). (4) i=n Note: For the case of s = 1 and t = 0, this reduces to N (1, n, r, N) and agrees with Theorem 7. Proof. The sequence B = (si + t)i≥n consists of all positive integers equivalent to t mod s that are greater than or equal to sn + t. For any positive integer p, the sum of any p elements of B is equivalent to pt mod s. In order to express all sufficiently large integers as the sum of r or more distinct elements of B, we need sums with the number of summands covering all equivalence classes of Zs . The list r, r + 1, r + 2, . . . , r + s − 1 contains representatives of each equivalence class in Zs . Since the integers s and t are relatively prime, the same is true for the list rt, (r + 1)t, (r + 2)t, . . . , (r + s − 1)t. Hence, all sums containing between r and r + s − 1 distinct elements of B will account for all sufficiently large positive integers, as we shall see. We must determine the smallest integer not expressible by one of these sums. For p ∈ {r, r + 1, r + 2, . . . , r + s − 1}, let mp be the sum of the first p elements of B, i.e., ! n+p−1 n+p−1 X X i + pt. (si + t) = s mp = i=n i=n As noted before, we have mp ≡ pt (mod s). We also know that mp is the smallest integer equivalent to pt mod s expressible as the sum of r or more distinct elements of B. Hence the integer mp − s is (1, n, r, (si + t)i∈N )-bad. If a positive integer x ≥ mp is also equivalent to pt mod s, then we have x = mp + ℓs for some positive ℓ ∈ Z or, equivalently, x = ℓs + n+p−1 n+p−2 X X (si + t) = (s(ℓ + n + p − 1) + t) + i=n i=n 7 (si + t). Thus, all integers equivalent to pt mod s greater than mp are expressible as the sum of r or more distinct elements of B. Since we have mp < mp+1 for all p, the last (1, n, r, (si + t)i∈N )bad integer is mr+s−1 − s. Therefore, the generalized anti-Waring number is N (1, n, r, (si + t)i∈N ) = mr+s−1 − s + 1 which is (4). k 1 2 3 4 5 6 N (k, 1) 1 129 12759 5134241 67898772 11146309948 x 1 4 5 8 4 5 b 4 18 32 59 45 55 bad count 0 31 2788 889576 13912682 2037573096 Table 1: Values of N (k, 1, 1, N) k 1 2 3 N (k, 1, 1, P) 7 17164 1866001 x 6 54 31 b 14 187 157 bad count 3 2438 483370 Table 2: Values of N (k, 1, 1, P) For most cases, a formula for N (k, n, r, A) is not known, but we can compute particular values. In the Tables 1 to 6 we list values of N (k, n, r, A) along with the corresponding x and b that satisfy the conditions for Theorem 6 hence confirming the given generalized antiWaring number. Tables 1, 3, and 4 use A = N. In Table 1 we consider n = r = 1, i.e., the first positive integer such that it and every subsequent integer can be written as the sum k th powers of distinct integers. For each k we also include a bad count, i.e., the number of positive integers that cannot be written as a sum of k th powers. Table 2 lists the corresponding values over the sequence of primes P. Table 3 lists generalized anti-Waring numbers for fixed n = 1 and varying k and r. We stopped the table at r = 36 but were able to compute some N (k, 1, r, N) for much larger r. For example, we found that N (2, 1, 1000, N) = 333951595 with x = 12898 and b = 19395. Table 4 lists generalized anti-Waring numbers for varying k, n, and r. Tables 3 and 4 omit generalized anti-Waring numbers when k = 1 because a formula for N (1, n, r, N) for all n and r in N exists by Theorem 7. Tables 5 and 6 list generalized anti-Waring numbers for fixed n = 1 and r = 1 over various sequences of the form (si + t)i∈N . 8 r 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 N (2, r) 129 129 129 129 198 238 331 383 528 648 889 989 1178 1398 1723 1991 2312 2673 3048 3493 4094 4614 5139 5719 6380 7124 7953 8677 9538 10394 11559 12603 13744 14864 16253 17529 x 4 4 4 4 6 6 8 9 10 12 14 15 17 19 21 24 26 28 31 34 36 39 42 44 48 51 54 57 61 63 67 71 74 78 81 85 b 18 18 18 18 22 23 26 27 32 33 39 41 44 47 52 54 58 62 65 69 75 79 83 87 91 96 101 105 109 114 120 125 130 135 141 146 N (3, r) 12759 12759 12759 12759 12759 15279 15279 15279 16224 18149 22398 24855 28887 36951 39660 49083 56076 66534 75912 87567 101093 122064 138696 156498 179520 201921 227400 256254 289869 325590 359358 401496 448503 496257 554217 611736 x 5 5 5 5 5 6 6 6 6 6 7 7 8 9 9 10 11 12 12 13 14 15 16 17 18 19 20 22 23 24 25 26 27 29 30 30 N (4, r) 5134241 5134241 5134241 5134241 5134241 5134241 5134241 5134241 5134241 5134241 5191473 5626194 6018930 6408466 6664722 6938867 8077523 8592323 9269124 10418260 10589380 12852837 13199973 15148358 16526214 17803895 20499591 21202776 24306872 25670088 29819129 31126025 35677050 38187306 43256507 46180043 b 32 32 32 32 32 33 33 33 33 35 37 38 39 42 43 46 47 50 52 54 56 60 62 64 67 69 72 73 76 79 82 85 88 90 93 97 x 8 8 8 8 8 8 8 8 8 8 8 8 8 9 9 9 9 9 10 10 10 11 11 11 12 12 13 13 13 14 14 15 15 16 16 17 b 59 59 59 59 59 59 59 59 59 59 59 60 62 62 62 63 66 67 67 69 70 72 73 76 76 78 81 81 84 84 88 88 92 92 96 97 N (5, r) 67898772 67898772 67898772 67898772 67898772 67898772 67898772 67898772 67898772 67898772 67898772 67898772 71780055 74729904 81846431 92894512 95723448 112031630 124811198 142118181 163637305 189572962 210715205 247073537 285744830 319712379 374237223 430026890 491665093 558015873 640101337 737104155 839165455 950792455 1070200765 1215652918 x 4 4 4 4 4 4 4 4 4 4 4 4 4 4 5 5 5 5 5 5 6 6 6 6 7 7 7 7 8 8 8 9 9 9 10 10 b 45 45 45 45 45 45 45 45 45 45 45 45 46 46 45 47 47 49 50 52 52 54 55 57 57 59 61 63 64 65 68 68 71 73 73 76 Table 3: Values of N (k, 1, r, N) and the corresponding x and b that satisfy Theorem 6. Values of N (1, n, r, N) are given by Theorem 7. 9 r 1 2 3 4 5 6 7 8 9 10 r 1 2 3 4 5 6 7 8 9 10 r 1 2 3 4 5 6 7 8 9 10 r 1 2 3 4 5 6 7 8 9 10 r 1 2 3 4 5 6 7 8 9 10 N (2, 2, r) 193 193 193 213 318 334 398 527 647 888 N (2, 3, r) 224 224 233 314 330 418 523 643 884 984 N (2, 4, r) 385 385 385 385 453 558 634 875 999 1164 N (2, 5, r) 493 493 493 494 542 670 883 983 1188 1412 N (2, 6, r) 637 637 637 637 834 870 958 1163 1387 1668 x 5 5 5 6 7 8 9 10 12 14 x 6 6 6 7 8 9 10 12 14 15 x 8 8 8 8 9 10 12 14 15 17 x 9 9 9 9 10 12 14 15 17 19 x 10 10 10 11 13 13 15 17 19 21 b 22 22 22 22 27 26 27 32 33 39 b 23 23 23 26 26 28 32 33 39 41 b 30 30 29 28 30 33 34 39 41 43 b 34 33 32 32 33 35 39 41 44 47 b 37 37 37 35 40 40 40 43 46 51 N (3, 2, r) 19310 19310 19310 19310 19310 19310 19310 19310 20885 24098 N (3, 3, r) 23775 23775 23775 23775 23775 23775 23775 24756 28221 28950 N (3, 4, r) 26862 26862 26862 26862 26862 26862 27528 28194 30111 33234 N (3, 5, r) 34844 34844 34844 34844 34844 34844 35060 35060 38048 43880 N (3, 6, r) 40416 40416 40416 40416 40416 40416 40416 41450 48066 49893 x 6 6 6 6 6 6 6 6 7 7 x 7 7 7 7 7 7 7 7 7 8 x 7 7 7 7 7 7 7 7 8 8 x 8 8 8 8 8 8 8 8 8 9 x 8 8 8 8 8 8 8 9 9 10 b 36 36 36 36 36 36 36 36 36 38 b 38 38 38 38 38 38 38 38 41 40 b 40 40 40 40 40 40 40 41 40 42 b 43 43 43 43 43 43 43 43 44 45 b 45 45 45 45 45 45 45 44 47 46 N (4, 2, r) 6659841 6659841 6659841 6659841 6659841 6692881 6692881 6692881 6778897 6778897 N (4, 3, r) 7076321 7076321 7076321 7076321 7076321 7076321 7103505 7103505 7103505 7103505 N (4, 4, r) 8912545 8912545 8912545 8912545 8912545 8912545 8912545 8912545 8912545 8912545 N (4, 5, r) 9292705 9292705 9292705 9292705 9292705 9377041 9377041 9377041 9377041 9377041 N (4, 6, r) 11728881 11728881 11728881 11728881 11728881 11728881 11728881 11728881 11728881 11728881 x 9 9 9 9 9 9 9 9 9 9 x 9 9 9 9 9 9 9 9 9 9 x 9 9 9 9 9 9 9 9 9 9 x 9 9 9 9 9 9 9 10 10 10 x 10 10 10 10 10 10 10 10 10 10 b 62 62 62 62 62 62 62 62 62 62 b 63 63 63 63 63 63 63 63 63 63 b 68 68 68 68 68 68 68 68 68 68 b 69 69 69 69 69 69 69 68 68 68 b 72 72 72 72 72 72 72 72 72 72 N (5, 2, r) 84038312 84038312 84038312 84038312 84038312 84038312 84038312 84038312 84038312 84038312 N (5, 3, r) 110100822 110100822 110100822 110100822 110100822 110100822 110100822 110100822 110100822 110100822 N (5, 4, r) 129436797 129436797 129436797 129436797 129436797 129436797 129436797 129436797 129436797 130964972 N (5, 5, r) 167956256 167956256 167956256 167956256 167956256 167956256 167956256 167956256 167956256 167956256 N (5, 6, r) 191116579 191116579 191116579 191116579 191116579 191116579 191116579 191116579 191116579 191116579 x 5 5 5 5 5 5 5 5 5 5 x 5 5 5 5 5 5 5 5 5 5 x 5 5 5 5 5 5 5 5 5 5 x 5 5 5 5 5 5 5 5 6 5 x 6 6 6 6 6 6 6 6 6 6 b 46 46 46 46 46 46 46 46 46 46 b 49 49 49 49 49 49 49 49 49 49 b 51 51 51 51 51 51 51 51 51 51 b 54 54 54 54 54 54 54 54 53 54 b 54 54 54 54 54 54 54 54 54 54 Table 4: Values of N (k, n, r, N) for n > 1 and the corresponding x and b that satisfy Theorem 6. Values of N (1, n, r, N) are given by Theorem 7. 10 (s, t) (2, −1) (2, +1) (3, −2) (3, −1) (3, +1) (3, +2) (4, −3) (4, −1) (4, +1) (4, +3) (5, −4) (5, −3) (5, −2) (5, −1) (5, +1) (5, +2) (5, +3) (5, +4) (6, −5) (6, −1) (6, +1) (6, +5) (7, −6) (7, −5) (7, −4) (7, −3) (7, −2) (7, −1) (7, +1) (7, +2) (7, +3) (7, +4) (7, +5) (7, +6) (8, −7) (8, −5) (8, −3) (8, −1) (8, +1) (8, +3) (8, +5) (8, +7) (9, −8) (9, −7) (9, −5) (9, −4) (9, −2) (9, −1) (9, +1) (9, +2) (9, +4) (9, +5) (9, +7) (9, +8) k=2 1923 2355 3250 3014 4093 4414 10588 11268 13708 14948 14900 14121 16810 16379 17242 19090 19690 19799 255964 261868 270796 282028 44329 45769 49737 49009 48989 49537 51889 55884 54217 60377 58292 63453 183828 186684 192748 199124 208164 216940 223884 227204 104873 114857 114653 118829 120113 130217 134681 129149 137873 141329 142825 149990 x 18 20 23 22 26 27 42 43 48 50 50 49 53 52 54 57 58 58 209 211 215 219 87 88 92 91 91 92 94 97 96 101 99 104 177 178 181 184 188 192 195 197 134 140 140 142 143 149 151 148 153 155 156 160 b 64 71 83 80 92 96 148 153 167 175 174 170 186 184 187 198 201 201 717 727 738 754 300 305 317 315 315 317 324 337 331 350 344 358 608 614 623 634 648 661 672 676 460 481 481 490 492 512 522 511 528 534 536 549 k=3 212595 266459 942316 957226 1103569 1181758 2576040 3026615 3152462 3534459 6146241 6373428 6672804 7077048 7165274 7526193 7821959 8326652 32025571 35431051 38008681 40622251 24233667 23668124 25473560 26139255 27035708 27348027 28963994 28297320 30183369 28992218 31374203 31015095 43603746 44323025 44594177 49916598 51794250 53940372 53774817 55157135 316621582 317215246 327375655 329700964 338139583 339498184 352115215 358747834 371854375 365220868 383482411 376489804 x 15 16 25 25 26 27 35 37 37 39 47 47 48 49 49 50 51 52 82 85 87 88 74 74 76 76 77 77 79 78 80 79 81 81 91 91 91 95 96 97 97 98 176 176 178 179 180 180 183 184 186 185 188 187 b 77 83 126 126 132 135 174 184 187 193 232 236 239 244 245 249 252 257 402 416 426 436 367 363 373 376 380 382 389 387 394 389 400 397 445 448 449 466 472 479 478 482 861 862 871 872 880 882 891 897 908 902 917 911 Table 5: Values of N (k, 1, 1, (si+t)i∈N ) and the corresponding x and b that satisfy Theorem 6. The generalized anti-Waring number N (k, n, r, (si + t)i∈N ) does not exist if gcd(s, t) > 1 by Theorem 1, and values of N (1, n, r, (si + t)i∈N ) are given by Theorem 8. 11 (s, t) (10, −1) (10, +1) (11, −1) (11, +1) (12, −1) (12, +1) (13, −1) (13, +1) (14, −1) (14, +1) (15, −1) (15, +1) (16, −1) (16, +1) (17, −1) (17, +1) (18, −1) (18, +1) (19, −1) (19, +1) (20, −1) (20, +1) k=2 2866844 2770803 251377 260001 1186948 1207948 484333 498269 14209388 14254244 878885 890945 4345668 4411364 1468737 1487777 47752420 47891524 2296953 2330393 12065164 12241324 x 701 689 207 211 451 455 288 292 1561 1563 388 390 863 869 501 505 2862 2866 627 632 1438 1449 b 2396 2356 711 723 1543 1556 986 1000 5333 5342 1328 1338 2950 2973 1717 1727 9774 9789 2146 2161 4915 4950 k=3 167900541 164930981 188148921 200560127 1871937463 1897625923 427144568 434996727 718660158 750996509 7192487965 7247153841 1162662009 1188105593 1528625985 1574453445 23390399911 23431535880 2670453204 2654207231 3392160594 3426870488 x 142 142 148 151 320 321 195 196 232 235 501 502 272 274 298 302 742 743 360 359 390 391 b 698 693 724 740 1555 1562 951 957 1130 1148 2434 2440 1328 1337 1454 1468 3606 3607 1750 1746 1895 1901 Table 6: Additional values of N (k, 1, 1, (si + t)i∈N ) and the corresponding x and b that satisfy Theorem 6. The generalized anti-Waring number N (k, n, r, (si + t)i∈N ) does not exist if gcd(s, t) > 1 by Theorem 1, and values of N (1, n, r, (si + t)i∈N ) are given by Theorem 8. 4 Future work With enough time and computing power, we can compute any values of N (k, n, r, A) that exist. However, we have only found a formula for cases with k = 1. Some simple inequalities involving N (k, n, r, A) are clear. For example, for i ≤ j we have the inequalities N (k, i, r, A) ≤ N (k, j, r, A) and N (k, n, i, A) ≤ N (k, n, j, A) when each exists. We are unable to prove the inequality N (k, n, r, A) ≤ N (k + 1, n, r, A) even though all data seem to emphatically support it. We have found and considered several algorithms for generating good numbers. However, none reveal a formula for the largest bad number, i.e., threshold of completeness for k > 1. 5 Acknowledgments We thank the editor and the anonymous referee for their time and consideration. The referee’s report was thorough and included valuable suggestions. 12 References [1] J. L. Brown, Jr., Note on complete sequences of integers, Amer. Math. Monthly 68 (1961), 557–560. [2] S. Burr and P. Erdős, Completeness properties of perturbed sequences, J. Number Theory 13 (1981), 446–455. [3] J. Deering and W. Jamieson, On anti-Waring numbers, to appear in J. Combin. Math. Combin. Comput. [4] R. Dressler and T. Parker, 12,758, Math. Comp. 28 (1974), 313–314. [5] C. Fuller, D. Prier, and K. Vasconi, New results on an anti-Waring problem, Involve 7 (2014), 239–244. [6] R. L. Graham, Complete sequences of polynomial values, Duke Math. J. 31 (1964), 275–285. [7] P. Johnson and M. Laughlin, An anti-Waring conjecture and problem, Int. J. Math. Comput. Sci. 6 (2011), 21–26. [8] T. Kløve, Sums of distinct elements from a fixed set, Math. Comp. 29 (1975), 1144–1149. [9] C. G. 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Zeckendorf, Représentation des nombres naturels par une somme de nombres de Fibonacci ou de nombres de Lucas, Bull. Soc. Roy. Sci. Liège 41 (1972), 179–182. 2010 Mathematics Subject Classification: Primary 11P05; Secondary 05A17. Keywords: complete sequence, sum of powers, anti-Waring number. (Concerned with sequence A001661.) Received June 18 2015; revised versions received September 13 2015; September 21 2015. Published in Journal of Integer Sequences, September 24 2015. Return to Journal of Integer Sequences home page. 14