A379173 G.f. A(x) satisfies A(x) = (1 + x)/(1 - x*A(x))^2.

1, 3, 11, 53, 284, 1630, 9794, 60830, 387390, 2515892, 16599051, 110943779, 749603067, 5111606801, 35133394554, 243146923574, 1692918638012, 11850006727400, 83341778073920, 588646472669454, 4173607638548291, 29694593381322531, 211941668053441490, 1517087043428034420

Offset

0,2

Links

Table of n, a(n) for n=0..23.

Formula

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

Prog

(PARI) a(n) = sum(k=0, n, binomial(n-k+1, k)*binomial(3*n-3*k+1, n-k)/(n-k+1));

Crossrefs

Cf. A003169, A249924, A379174.

Cf. A025227, A379171.

Sequence in context: A053557 A039302 A074512 * A005502 A305710 A351200

Adjacent sequences: A379170 A379171 A379172 * A379174 A379175 A379176

Keyword

nonn

Author

Seiichi Manyama, Dec 17 2024

Status

approved