OFFSET
0,5
FORMULA
G.f.: Sum_{k>=0} x^k/Product_{j=1..k} (1 - j * x^3).
MATHEMATICA
Table[Sum[StirlingS2[n-2k, n-3k], {k, 0, Floor[n/3]}], {n, 0, 40}] (* Harvey P. Dale, Feb 22 2024 *)
PROG
(PARI) a(n) = sum(k=0, n\3, stirling(n-2*k, n-3*k, 2));
(PARI) my(N=40, x='x+O('x^N)); Vec(sum(k=0, N, x^k/prod(j=1, k, 1-j*x^3)))
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Oct 20 2022
STATUS
approved