OFFSET
0,2
FORMULA
a(n) = Sum_{k=0..n} k^k * (n-k)!.
a(n) ~ n^n * (1 + exp(-1)/n).
MATHEMATICA
Table[Sum[If[k == 0, 1, k^k] * (n-k)!, {k, 0, n}], {n, 0, 20}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Vaclav Kotesovec, Mar 08 2018
STATUS
approved