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A322539 Number of arrays of n integers in -9..9 with sum zero. 2
1, 1, 19, 271, 4579, 78151, 1363573, 24072133, 429042211, 7702189345, 139071924069, 2522948398895, 45949039890469, 839611990929219, 15385356833972711, 282616668487409521, 5202536118941844771, 95950964483217949751, 1772592132899627652691 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Seiichi Manyama, Table of n, a(n) for n = 0..300

FORMULA

a(n) = [x^(9*n)] (Sum_{k=0..18} x^k)^n.

a(n) ~ 19^n / (2*sqrt(15*Pi*n)). - Vaclav Kotesovec, Dec 15 2018

MATHEMATICA

a[n_] := If[n==0, 1, Coefficient[Expand[Sum[x^k, {k, 0, 18}]^n], x^(9n)]]; Array[a, 25, 0] (* Amiram Eldar, Dec 14 2018 *)

PROG

(PARI) {a(n) = polcoeff((sum(k=0, 18, x^k))^n, 9*n, x)}

CROSSREFS

Column 9 of A201552.

Sequence in context: A016189 A125476 A016248 * A199819 A016187 A016184

Adjacent sequences:  A322536 A322537 A322538 * A322540 A322541 A322542

KEYWORD

nonn

AUTHOR

Seiichi Manyama, Dec 14 2018

STATUS

approved

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Last modified October 16 13:09 EDT 2019. Contains 328064 sequences. (Running on oeis4.)