A336247 a(n) = (n!)^n * Sum_{k=0..n} 1 / (k!)^n.

1, 2, 9, 460, 684545, 50547203126, 280807908057046657, 165858480204085842350156792, 13997217669604247492958380810030809089, 218434494471443385260764665498960241287478619115850, 792268399795067334328715213043856435592857850955707257780000000001

Offset: 0

Author

Ilya Gutkovskiy, Jul 14 2020

Keywords

• nonn

Links

• Seiichi Manyama, Table of n, a(n) for n = 0..30

Crossrefs

Cf. A000522, A006040, A036740, A060943, A217284, A336248.

Main diagonal of A343863.

Programs

Mathematica

Table[(n!)^n Sum[1/(k!)^n, {k, 0, n}], {n, 0, 10}]

PARI

a(n) = (n!)^n * sum(k=0, n, 1/(k!)^n); \\ Michel Marcus, Jul 14 2020