A371387 Expansion of (1/x) * Series_Reversion( x * (1-4*x)^3 / (1-x) ).

1, 11, 205, 4647, 116873, 3135635, 87924597, 2545845135, 75534363601, 2284439539035, 70166186106333, 2182759455876663, 68630655620066265, 2177561996773904483, 69632831106680348165, 2241852665024904670239, 72608750028928583936673

Offset

0,2

Links

Table of n, a(n) for n=0..16.

Index entries for reversions of series

Formula

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

Prog

(PARI) my(N=20, x='x+O('x^N)); Vec(serreverse(x*(1-4*x)^3/(1-x))/x)
(PARI) a(n) = sum(k=0, n, 3^k*binomial(3*n+k+2, k)*binomial(3*n+1, n-k))/(n+1);

Crossrefs

Cf. A131763, A371386.

Cf. A371365.

Sequence in context: A091814 A280957 A020518 * A196849 A373348 A196699

Adjacent sequences: A371384 A371385 A371386 * A371388 A371389 A371390

Keyword

nonn

Author

Seiichi Manyama, Mar 20 2024

Status

approved