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A369618 revision #7

A369618

Expansion of (1/x) * Series_Reversion( x / (1/(1-x) + x^2) ).

1, 1, 3, 8, 26, 87, 308, 1122, 4196, 15995, 61953, 243091, 964307, 3860820, 15581231, 63318119, 258874412, 1064093055, 4394851631, 18229191263, 75904152261, 317161817092, 1329465389854, 5589012748902, 23558679647629, 99548061405442, 421598837336178

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,3

LINKS

Table of n, a(n) for n=0..26.

Index entries for reversions of series

FORMULA

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

PROG

(PARI) my(N=30, x='x+O('x^N)); Vec(serreverse(x/(1/(1-x)+x^2))/x)

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

CROSSREFS