A034716 Dirichlet convolution of factorials with themselves.

1, 4, 12, 52, 240, 1464, 10080, 80736, 725796, 7258080, 79833600, 958006368, 12454041600, 174356602560, 2615348737440, 41845579937856, 711374856192000, 12804747412916160, 243290200817664000, 4865804016367800960, 102181884343418940480, 2248001455555375027200

Offset

1,2

Links

Seiichi Manyama, Table of n, a(n) for n = 1..449

Formula

a(n) ~ 2 * n!. - Vaclav Kotesovec, Jan 28 2019

Mathematica

Table[Sum[d!*(n/d)!, {d, Divisors[n]}], {n, 1, 25}] (* Vaclav Kotesovec, Jan 28 2019 *)

Prog

(PARI) a(n)=sumdiv(n, d, (d!) * (n/d)! );  /* Joerg Arndt, Oct 07 2012 */

Crossrefs

Sequence in context: A188230 A124006 A215524 * A129841 A277431 A065525

Adjacent sequences: A034713 A034714 A034715 * A034717 A034718 A034719

Keyword

nonn

Author

Erich Friedman

Status

approved