OFFSET
0,3
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..200
Vladimir Kruchinin and D. V. Kruchinin, Composita and their properties , arXiv:1103.2582 [math.CO], 2011-2013.
FORMULA
E.g.f.: exp(x)*(1-x)^(-x).
a(n) = sum(k=0..n, C(n,k) *sum(j=0..k, C(k,j) *abs(Stirling1(n-k,j)) *j!)).
a(n) ~ n! * exp(1). - Vaclav Kotesovec, Aug 13 2013
MAPLE
with(combinat):
a:= n-> add(binomial(n, k) *add(binomial(k, j)
*abs(stirling1(n-k, j)) *j!, j=0..k), k=0..n):
seq(a(n), n=0..20); # Alois P. Heinz, Feb 03 2011
MATHEMATICA
With[{nn=25}, CoefficientList[Series[Exp[x](1-x)^-x, {x, 0, nn}], x] Range[0, nn]!] (* Harvey P. Dale, Oct 26 2011 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Vladimir Kruchinin, Feb 02 2011
STATUS
approved