A360087 a(n) = Sum_{k=0..n} (-1)^k * binomial(3*k,n-k).

1, -1, -2, 2, 6, -5, -17, 12, 48, -28, -135, 63, 378, -134, -1054, 259, 2927, -408, -8096, 280, 22305, 1551, -61210, -10638, 167310, 46683, -455489, -175852, 1234960, 612380, -3334215, -2031953, 8962498, 6523626, -23981046, -20445373, 63855135, 62900496

Offset

0,3

Links

Table of n, a(n) for n=0..37.

Index entries for linear recurrences with constant coefficients, signature (-1,-3,-3,-1).

Formula

a(n) = -a(n-1) - 3*a(n-2) - 3*a(n-3) - a(n-4).

G.f.: 1/(1 + x*(1+x)^3).

Prog

(PARI) a(n) = sum(k=0, n, (-1)^k*binomial(3*k, n-k));
(PARI) my(N=40, x='x+O('x^N)); Vec(1/(1+x*(1+x)^3))

Crossrefs

Cf. A077979, A360088, A360089.

Cf. A099234.

Sequence in context: A201500 A054917 A111419 * A306768 A174399 A056881

Adjacent sequences: A360084 A360085 A360086 * A360088 A360089 A360090

Keyword

sign,easy

Author

Seiichi Manyama, Jan 25 2023

Status

approved