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A322540 Number of arrays of n integers in -10..10 with sum zero. 2
1, 1, 21, 331, 6181, 116601, 2248575, 43874139, 864287973, 17148949027, 342237634221, 6862175029689, 138132246844879, 2789732439723061, 56501091296763855, 1147129435985083731, 23339695295337149925, 475767618472211229549 (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^(10*n)] (Sum_{k=0..20} x^k)^n.

a(n) ~ sqrt(3) * 21^n / (2*sqrt(55*Pi*n)). - Vaclav Kotesovec, Dec 15 2018

MATHEMATICA

a[n_] := If[n==0, 1, Coefficient[Expand[Sum[x^k, {k, 0, 20}]^n], x^(10n)]]; Array[a, 25, 0] (* Amiram Eldar, Dec 14 2018 *)

PROG

(PARI) {a(n) = polcoeff((sum(k=0, 20, x^k))^n, 10*n, x)}

CROSSREFS

Column 10 of A201552.

Sequence in context: A011810 A091947 A016195 * A016191 A297336 A095905

Adjacent sequences:  A322537 A322538 A322539 * A322541 A322542 A322543

KEYWORD

nonn

AUTHOR

Seiichi Manyama, Dec 14 2018

STATUS

approved

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Last modified July 20 05:56 EDT 2019. Contains 325168 sequences. (Running on oeis4.)