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 A201551 Number of arrays of n integers in -7..7 with sum zero. 3
 1, 1, 15, 169, 2255, 30381, 418503, 5832765, 82073295, 1163205475, 16581420835, 237481736823, 3414582082055, 49258226347903, 712601187601395, 10334165623697259, 150186639579545295, 2186774434431445455 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS Seiichi Manyama, Table of n, a(n) for n = 0..400 (terms 1..210 from R. H. Hardin) [It was suggested that the initial terms of this b-file were wrong, but in fact they are correct. - N. J. A. Sloane, Jan 19 2019] FORMULA a(n) ~ sqrt(3) * 15^n / (4*sqrt(7*Pi*n)). - Vaclav Kotesovec, Dec 15 2018 EXAMPLE Some solutions for n=5 .-6....6....2...-1...-4...-5...-2...-2....4...-6....2....7...-5...-5....3....5 .-2....0....7...-3....2....6...-3....7...-4...-2...-7...-3....6....2...-3...-7 ..0...-6...-5...-2....6....5....5...-5...-6....5....5....1...-4....4....1...-4 ..2...-2...-4....0...-7...-5....6...-7....6....6...-5....1....4....5...-3....7 ..6....2....0....6....3...-1...-6....7....0...-3....5...-6...-1...-6....2...-1 MATHEMATICA a[n_] := If[n==0, 1, Coefficient[Expand[Sum[x^k, {k, 0, 14}]^n], x^(7n)]]; Array[a, 25, 0] (* Amiram Eldar, Dec 14 2018 *) PROG (PARI) {a(n) = polcoeff((sum(k=0, 14, x^k))^n, 7*n, x)} \\ Seiichi Manyama, Dec 14 2018 CROSSREFS Column 7 of A201552. Sequence in context: A016279 A036734 A201041 * A339770 A240276 A206600 Adjacent sequences: A201548 A201549 A201550 * A201552 A201553 A201554 KEYWORD nonn AUTHOR R. H. Hardin, Dec 02 2011 EXTENSIONS a(0)=1 prepended by Seiichi Manyama, Dec 14 2018 STATUS approved

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Last modified March 22 17:42 EDT 2023. Contains 361432 sequences. (Running on oeis4.)