A369691 G.f. satisfies A(x) = 1/(1-x)^3 + x^3*A(x)^3.

1, 3, 6, 11, 24, 66, 196, 576, 1692, 5110, 15933, 50604, 161988, 521700, 1693362, 5541679, 18260055, 60487659, 201272437, 672550158, 2256204327, 7596059333, 25655943417, 86904524289, 295154911774, 1004906765178, 3429178160346, 11726499288028, 40178538608682

Offset

0,2

Links

Table of n, a(n) for n=0..28.

Formula

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

Prog

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

Crossrefs

Cf. A364623, A364626.

Cf. A086615, A369693.

Cf. A364589.

Sequence in context: A346050 A319636 A001867 * A000998 A331536 A365294

Adjacent sequences: A369688 A369689 A369690 * A369692 A369693 A369694

Keyword

nonn

Author

Seiichi Manyama, Jan 29 2024

Status

approved