OFFSET
0,2
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..10000
Index entries for linear recurrences with constant coefficients, signature (9, -36, 84, -126, 126, -84, 36, -9, 1).
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
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Dec 14 2018
STATUS
approved