A373520 Expansion of e.g.f. exp(x/(1 - x^4)^(1/2)).

1, 1, 1, 1, 1, 61, 361, 1261, 3361, 143641, 1829521, 12501721, 59922721, 2173048021, 44315751481, 478799701381, 3492321094081, 116722067432881, 3290135175240481, 50242015215929521, 508061488330088641, 16418736123292904941, 585427887134915295241

Offset

0,6

Links

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

Formula

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

a(n) == 1 mod 60.

Prog

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

Crossrefs

Cf. A293507, A373519, A373521.

Cf. A373525.

Sequence in context: A373525 A357965 A353225 * A189174 A304062 A305454

Adjacent sequences: A373517 A373518 A373519 * A373521 A373522 A373523

Keyword

nonn

Author

Seiichi Manyama, Jun 08 2024

Status

approved