A366200 G.f. A(x) satisfies A(x) = 1 + x*(1 + x)^3*A(x)^3.

1, 1, 6, 33, 209, 1425, 10206, 75751, 577494, 4495368, 35582439, 285524184, 2317387098, 18990744137, 156918815760, 1305927563487, 10936673012579, 92098612059051, 779391530714589, 6624730079900931, 56532669993156696, 484156547579505717, 4159926573597719575

Offset

0,3

Links

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

Formula

a(n) = Sum_{k=0..n} binomial(3*k,n-k) * binomial(3*k,k)/(2*k+1).

Prog

(PARI) a(n) = sum(k=0, n, binomial(3*k, n-k)*binomial(3*k, k)/(2*k+1));

Crossrefs

Cf. A073155, A366216.

Sequence in context: A361776 A193665 A097662 * A277485 A012522 A012326

Adjacent sequences: A366197 A366198 A366199 * A366201 A366202 A366203

Keyword

nonn

Author

Seiichi Manyama, Oct 04 2023

Status

approved