A378404 a(n) = Sum_{k=0..n} binomial(n,k) * binomial(n+3*k,n-k).

1, 2, 12, 74, 464, 2997, 19704, 131140, 880912, 5960000, 40555117, 277251834, 1902791048, 13101878220, 90468268336, 626202992439, 4343671952768, 30186478566432, 210131106485088, 1464920605002240, 10226302297174509, 71474029751497258, 500097817634501780

Offset

0,2

Links

Table of n, a(n) for n=0..22.

Formula

a(n) = [x^n] (1 + x + x * (1 + x)^4)^n.

Prog

(PARI) a(n) = sum(k=0, n, binomial(n, k)*binomial(n+3*k, n-k));

Crossrefs

Cf. A000984, A082759, A378403.

Sequence in context: A020004 A078469 A014351 * A360318 A074616 A370242

Adjacent sequences: A378401 A378402 A378403 * A378405 A378406 A378407

Keyword

nonn

Author

Seiichi Manyama, Nov 25 2024

Status

approved