A373521 Expansion of e.g.f. exp(x/(1 - x^4)^(3/4)).

1, 1, 1, 1, 1, 91, 541, 1891, 5041, 249481, 3424681, 24365881, 119821681, 4208219731, 96849813061, 1133147785771, 8728726799521, 251218306095121, 8116398738418321, 138787857114672241, 1523943014238675361, 39648007379230971211, 1599866285860593980461

Offset

0,6

Links

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

Formula

a(n) = n! * Sum_{k=0..floor(n/4)} binomial(3*n/4-2*k-1,k)/(n-4*k)!.

a(n) == 1 mod 90.

Prog

(PARI) a(n) = n!*sum(k=0, n\4, binomial(3*n/4-2*k-1, k)/(n-4*k)!);

Crossrefs

Cf. A293507, A373519, A373520.

Cf. A373526.

Sequence in context: A234131 A234124 A373526 * A180942 A211447 A188360

Adjacent sequences: A373518 A373519 A373520 * A373522 A373523 A373524

Keyword

nonn

Author

Seiichi Manyama, Jun 08 2024

Status

approved