A321951 Column k=6 of triangle A257673.

1, 18, 171, 1158, 6309, 29466, 122580, 465738, 1644516, 5464892, 17253369, 52128540, 151592391, 426265836, 1163373243, 3091338000, 8018585046, 20348618814, 50615278427, 123608650182, 296794147017, 701525018576, 1634144413185, 3755097200094, 8519488746222

Offset: 6

Author

Alois P. Heinz, Nov 22 2018

Keywords

• nonn

Links

• Alois P. Heinz, Table of n, a(n) for n = 6..5000

Crossrefs

Column k=6 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))(6):
seq(a(n), n=6..35);

Formula

G.f.: (-1 + Product_{k>=1} 1 / (1 - x^k)^k)^6. - Ilya Gutkovskiy, Jan 30 2021