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A357902
a(n) = Sum_{k=0..floor(n/4)} |Stirling1(n - 3*k,k)|.
4
1, 0, 0, 0, 1, 1, 2, 6, 25, 123, 731, 5090, 40595, 364650, 3641903, 40026609, 480029801, 6237662582, 87298953249, 1309161984315, 20942605407386, 355971044728635, 6406714801013007, 121715861296354116, 2434125806029297550, 51113325326999860554, 1124432395936987325868
OFFSET
0,7
FORMULA
G.f.: Sum_{k>=0} x^k * Product_{j=0..k-1} (j + x^3).
PROG
(PARI) a(n) = sum(k=0, n\4, abs(stirling(n-3*k, k, 1)));
(PARI) my(N=30, x='x+O('x^N)); Vec(sum(k=0, N, x^k*prod(j=0, k-1, j+x^3)))
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Oct 19 2022
STATUS
approved