A375826 E.g.f. satisfies A(x) = 1/(1 - x*A(x))^(x^2).

1, 0, 0, 6, 12, 40, 1260, 11088, 99120, 1926720, 32800320, 535328640, 11274642720, 259872088320, 6108539621184, 158608655251200, 4495317057504000, 134114095312404480, 4253953999500357120, 143971794376985272320, 5141239842495675340800

Offset

0,4

Links

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

Formula

a(n) = n! * Sum_{k=0..floor(n/3)} (n-2*k+1)^(k-1) * |Stirling1(n-2*k,k)|/(n-2*k)!.

Prog

(PARI) a(n) = n!*sum(k=0, n\3, (n-2*k+1)^(k-1)*abs(stirling(n-2*k, k, 1))/(n-2*k)!);

Crossrefs

Cf. A001761, A349559.

Cf. A375827.

Sequence in context: A351503 A371118 A355287 * A362891 A371302 A371233

Adjacent sequences: A375823 A375824 A375825 * A375827 A375828 A375829

Keyword

nonn

Author

Seiichi Manyama, Aug 30 2024

Status

approved