OFFSET
4,3
LINKS
Vaclav Kotesovec, Table of n, a(n) for n = 4..10000 (terms 4..1000 from Alois P. Heinz)
N. J. A. Sloane, Transforms
FORMULA
Euler transform of A002865 (with a(0)=0) shifted right.
MATHEMATICA
T[n_, k_] := T[n, k] = If[n == 1, 1, If[k == 0, 0, Sum[Sum[If[d < k, 0, T[d, k - 1]*d], {d, Divisors[j]}]*T[n - j, k], {j, 1, n - 1}]/(n - 1)]];
a[n_] := T[n, 3];
CROSSREFS
KEYWORD
nonn
AUTHOR
Christian G. Bower, Apr 15 1999
STATUS
approved