A321950 Column k=5 of triangle A257673.

1, 15, 120, 695, 3285, 13473, 49730, 169115, 538440, 1623660, 4677121, 12955065, 34682730, 90113220, 227992870, 563267203, 1361992935, 3229643480, 7522847555, 17237982025, 38905739524, 86585024910, 190193593830, 412712252535, 885382820550, 1879084411753

Offset: 5

Author

Alois P. Heinz, Nov 22 2018

Keywords

• nonn

Links

• Alois P. Heinz, Table of n, a(n) for n = 5..5000

Crossrefs

Column k=5 of A257673.

Programs

Maple

b:= proc(n, k) option remember; `if`(n=0, 1, k*add(
      b(n-j, k)*numtheory[sigma][2](j), j=1..n)/n)
    end:
a:= n-> (k-> add(b(n, k-i)*(-1)^i*binomial(k, i), i=0..k))(5):
seq(a(n), n=5..35);

Formula

G.f.: (-1 + Product_{k>=1} 1 / (1 - x^k)^k)^5. - Ilya Gutkovskiy, Jan 30 2021