A034716 - OEIS

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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

(list; graph; refs; listen; history; text; internal format)

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