OFFSET
0,3
FORMULA
a(n) = A317172(n)/n = Sum_{k=0..n} k!*n^(k-1)*Stirling1(n,k) for n > 1.
a(n) ~ sqrt(2*Pi) * n^(2*n - 1/2) / exp(n + 1/2). - Vaclav Kotesovec, Jun 12 2020
MATHEMATICA
a[0] = 1; a[n_] := Sum[k! * n^(k - 1) * StirlingS1[n, k], {k, 0, n}]; Array[a, 17, 0] (* Amiram Eldar, Jun 12 2020 *)
PROG
(PARI) {a(n) = if(n==0, 1, sum(k=0, n, k!*n^(k-1)*stirling(n, k, 1)))}
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Jun 12 2020
STATUS
approved