A350268 a(n) = Sum_{k=0..n} (n - k)! * (n - 1)^k. Row sums of A350269.

1, 1, 4, 22, 168, 1720, 22670, 368784, 7134148, 159416704, 4027395330, 113235212800, 3501763366904, 118024658758656, 4303855119215782, 168777440194263040, 7081468496171815500, 316501174908316647424, 15010862087643791689322, 752916261526858377363456

Offset: 0

Author

Peter Luschny, Dec 25 2021

Keywords

• nonn

Crossrefs

Cf. A350269.

Programs

Mathematica

a[1] = 1; a[n_] := Sum[(n - k)! * (n - 1)^k, {k, 0, n}]; Array[a, 20, 0] (* Amiram Eldar, Dec 25 2021 *)

PARI

a(n) = sum(k=0, n, (n-k)!*(n-1)^k); \\ Michel Marcus, Dec 25 2021