OFFSET
0,3
FORMULA
a(n) = sum(abs(stirling1(n,k)*stirling1(n+1,k+1)*stirling1(n+2,k+2)),k=0..n).
MATHEMATICA
Table[Sum[Abs[StirlingS1[n, k]StirlingS1[n+1, k+1]StirlingS1[n+2, k+2]], {k, 0, n}], {n, 0, 100}]
PROG
(Maxima) makelist(sum(abs(stirling1(n, k)*stirling1(n+1, k+1)*stirling1(n+2, k+2)), k, 0, n), n, 0, 24);
CROSSREFS
KEYWORD
nonn
AUTHOR
Emanuele Munarini, Jul 04 2011
STATUS
approved