A371380 Expansion of (1/x) * Series_Reversion( x * (1-3*x)^2 / (1-x) ).

1, 5, 46, 521, 6574, 88658, 1250920, 18236849, 272544886, 4153080950, 64284022516, 1007929418570, 15974993572732, 255522850658564, 4119461259700060, 66869059171095809, 1091990982773631910, 17927521032225339854, 295717190725184361364, 4898634803627227516238

Offset

0,2

Links

Table of n, a(n) for n=0..19.

Index entries for reversions of series

Formula

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

Prog

(PARI) my(N=30, x='x+O('x^N)); Vec(serreverse(x*(1-3*x)^2/(1-x))/x)
(PARI) a(n) = sum(k=0, n, 2^k*binomial(2*n+k+1, k)*binomial(2*n, n-k))/(n+1);

Crossrefs

Cf. A107841, A371385.

Cf. A371362.

Sequence in context: A232972 A127304 A112029 * A295544 A375436 A058478

Adjacent sequences: A371377 A371378 A371379 * A371381 A371382 A371383

Keyword

nonn

Author

Seiichi Manyama, Mar 20 2024

Status

approved