A322536 Number of arrays of 9 integers in -n..n with sum zero.

1, 3139, 180325, 2636263, 19610233, 97464799, 370487485, 1163205475, 3164588407, 7702189345, 17148949027, 35500063501, 69161990275, 128000343121, 226698100687, 386480229085, 637265493637, 1020310909975, 1591418959705, 2424782370859, 3617545938373, 5295169534843

Offset

0,2

Links

Seiichi Manyama, Table of n, a(n) for n = 0..10000

Formula

a(n) = [x^(9*n)] (Sum_{k=0..2*n} x^k)^9.

Mathematica

a[n_] := Coefficient[Expand[Sum[x^k, {k, 0, 2n}]^9, x], x, 9n]; Array[a, 25, 0] (* Amiram Eldar, Dec 14 2018 *)

Prog

(PARI) {a(n) = polcoeff((sum(k=0, 2*n, x^k))^9, 9*n, x)}

Crossrefs

Row 9 of A201552.

Sequence in context: A187645 A187640 A187639 * A172641 A172744 A172819

Adjacent sequences: A322533 A322534 A322535 * A322537 A322538 A322539

Keyword

nonn

Author

Seiichi Manyama, Dec 14 2018

Status

approved