A357932 a(n) = Sum_{k=0..floor(n/4)} |Stirling1(n - 3*k,n - 4*k)|.

1, 1, 1, 1, 1, 2, 4, 7, 11, 18, 33, 64, 122, 227, 428, 838, 1684, 3396, 6841, 13912, 28787, 60398, 127559, 270687, 579055, 1251706, 2730345, 5994501, 13238058, 29436628, 65951104, 148777927, 337606123, 770418129, 1768566987, 4084504483, 9486890220

Offset: 0

Author

Seiichi Manyama, Oct 21 2022

Keywords

• nonn

Crossrefs

Cf. A124380, A357931, A357933.

Cf. A353225, A357902, A357926.

Programs

PARI

a(n) = sum(k=0, n\4, abs(stirling(n-3*k, n-4*k, 1)));

PARI

my(N=40, x='x+O('x^N)); Vec(sum(k=0, N, x^k*prod(j=0, k-1, 1+j*x^3)))

Formula

G.f.: Sum_{k>=0} x^k * Product_{j=0..k-1} (1 + j * x^3).