A366564 Expansion of e.g.f. -log(1 - x^2 * (exp(x) - 1)).

0, 0, 0, 6, 12, 20, 390, 2562, 11816, 166392, 1970730, 17131070, 241009692, 3861669396, 51411143966, 828234487290, 15865154629200, 283329069136112, 5431892804244306, 119420738547382134, 2628980439169097540, 59707303735169923980, 1488953374718002643142

Offset

0,4

Links

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

Formula

a(n) = n! * Sum_{k=1..floor(n/3)} (k-1)! * Stirling2(n-2*k,k)/(n-2*k)!.

Prog

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

Crossrefs

Cf. A052858, A366751.

Cf. A366459, A368173.

Sequence in context: A247256 A292951 A240989 * A247212 A358013 A371116

Adjacent sequences: A366561 A366562 A366563 * A366565 A366566 A366567

Keyword

nonn

Author

Seiichi Manyama, Dec 15 2023

Status

approved