A369156 Expansion of (1/x) * Series_Reversion( x / ((1+x)^4-x^4) ).

1, 4, 22, 140, 968, 7064, 53544, 417456, 3326304, 26967040, 221733568, 1844667136, 15498804480, 131325820032, 1120928667264, 9628975973120, 83181462291968, 722175844640768, 6297942966129664, 55143987250677760, 484589284705202176, 4272491458636754944

Offset

0,2

Links

Table of n, a(n) for n=0..21.

Index entries for reversions of series

Formula

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

Prog

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

Crossrefs

Cf. A107264, A369157.

Cf. A317133, A369126.

Sequence in context: A325453 A216712 A240586 * A002293 A181784 A369126

Adjacent sequences: A369153 A369154 A369155 * A369157 A369158 A369159

Keyword

nonn

Author

Seiichi Manyama, Jan 15 2024

Status

approved