OFFSET
0,3
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..273
FORMULA
a(n) = (1/(2e)) * Sum_{r,s >= 0} (r*s)^n / (2^r*s!).
MAPLE
a:= n-> combinat[bell](n)*add(Stirling2(n, k)*k!, k=0..n): seq(a(n), n=0..19); # Zerinvary Lajos, Sep 30 2006
MATHEMATICA
Table[BellB[n]*Sum[StirlingS2[n, k]*k!, {k, 0, n}], {n, 0, 17}] (* James C. McMahon, Oct 11 2024 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Vladeta Jovovic, Sep 08 2006
EXTENSIONS
More terms from Zerinvary Lajos, Sep 30 2006
STATUS
approved