OFFSET
0,3
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..379 (first 101 terms from T. D. Noe)
FORMULA
E.g.f.: B(e^x-1) where B is e.g.f. of A000272.
a(n) = Sum_{k=1..n} Stirling2(n, k)*k^(k-2). - Vladeta Jovovic, Sep 20 2003
a(n) ~ (1+exp(1))^(3/2) * n^(n-2) / (exp(n) * (log(1+exp(-1)))^(n-3/2)). - Vaclav Kotesovec, Feb 17 2017
MAPLE
b:= proc(n, m) option remember; `if`(n=0,
m^max(0, m-2), m*b(n-1, m)+b(n-1, m+1))
end:
a:= n-> b(n, 0):
seq(a(n), n=0..21); # Alois P. Heinz, Jul 16 2022
MATHEMATICA
a[0] = 1; a[n_] := Sum[StirlingS2[n, k]*k^(k - 2), {k, 1, n}]; Table[a[n], {n, 0, 18}] (* Jean-François Alcover, Sep 09 2013, after Vladeta Jovovic *)
CROSSREFS
KEYWORD
nonn,nice,easy
AUTHOR
Christian G. Bower, Jan 04 1999
STATUS
approved