A373682 Expansion of e.g.f. exp(x / (1 - x^2)^3) / (1 - x^2).

1, 1, 3, 25, 109, 1401, 11191, 147673, 1887705, 26419249, 454408651, 7265533881, 148341346693, 2804459457385, 63733061703039, 1419987630142201, 35144931608633521, 902380834051682913, 24277141650582775315, 699721521711883149529, 20520810981571082937501

Offset

0,3

Links

Table of n, a(n) for n=0..20.

Formula

a(n) = n! * Sum_{k=0..floor(n/2)} binomial(3*n-5*k,k)/(n-2*k)!.

a(n) == 1 (mod 2).

Prog

(PARI) a(n) = n!*sum(k=0, n\2, binomial(3*n-5*k, k)/(n-2*k)!);

Crossrefs

Cf. A373681, A373683.

Cf. A373668.

Sequence in context: A180324 A124245 A360788 * A166899 A201534 A059457

Adjacent sequences: A373679 A373680 A373681 * A373683 A373684 A373685

Keyword

nonn

Author

Seiichi Manyama, Jun 13 2024

Status

approved