A391379 Expansion of g^2/(1 + x*g^2), where g = 1+x*g^4 is the g.f. of A002293.

1, 1, 6, 35, 232, 1646, 12239, 94137, 742825, 5980056, 48922556, 405553786, 3399234751, 28759383055, 245284421794, 2106648344723, 18204169010624, 158160107826385, 1380740162723725, 12105923730466112, 106553900171498799, 941167605177271396, 8339751316507463238

Offset

0,3

Links

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

Formula

a(n) = Sum_{k=0..n} (-1)^k * (k+1) * binomial(4*n-2*k+2,n-k)/(2*n-k+1).

Prog

(PARI) a(n) = sum(k=0, n, (-1)^k*(k+1)*binomial(4*n-2*k+2, n-k)/(2*n-k+1));

Crossrefs

Cf. A002293, A390740.

Sequence in context: A145145 A367234 A357828 * A347002 A346945 A289383

Adjacent sequences: A391376 A391377 A391378 * A391380 A391381 A391382

Keyword

nonn

Author

Seiichi Manyama, Dec 07 2025

Status

approved