A368932 Expansion of (1/x) * Series_Reversion( x * (1-x) * (1-x-x^4) ).

1, 2, 7, 30, 144, 741, 3996, 22287, 127495, 743941, 4410555, 26492349, 160875186, 986007700, 6091548256, 37894543413, 237168491610, 1492323419929, 9434943086870, 59906035386393, 381832957589226, 2442251022673595, 15670578495195870

Offset

0,2

Links

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

Formula

a(n) = (1/(n+1)) * Sum_{k=0..floor(n/4)} binomial(n+k,k) * binomial(3*n-3*k+1,n-4*k).

Prog

(PARI) a(n) = sum(k=0, n\4, binomial(n+k, k)*binomial(3*n-3*k+1, n-4*k))/(n+1);
(PARI) my(N=30, x='x+O('x^N)); Vec(serreverse(x*(1-x)*(1-x-x^4))/x)

Crossrefs

Cf. A236339, A368931, A368933.

Cf. A063021, A215342.

Sequence in context: A187979 A358964 A366055 * A369160 A243632 A196148

Adjacent sequences: A368929 A368930 A368931 * A368933 A368934 A368935

Keyword

nonn

Author

Seiichi Manyama, Jan 10 2024

Status

approved