A321952 Column k=7 of triangle A257673.

1, 21, 231, 1792, 11067, 58044, 268940, 1129999, 4385136, 15928948, 54711958, 179090772, 562156203, 1700628930, 4978677738, 14153099499, 39180254316, 105881154624, 279906223856, 725158329175, 1844006226090, 4608929551309, 11336379967178, 27469729015029

Offset

7,2

Links

Alois P. Heinz, Table of n, a(n) for n = 7..5000

Formula

G.f.: (-1 + Product_{k>=1} 1 / (1 - x^k)^k)^7. - Ilya Gutkovskiy, Jan 30 2021

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))(7):
seq(a(n), n=7..35);

Crossrefs

Column k=7 of A257673.

Sequence in context: A247615 A010973 A022586 * A125409 A161581 A350570

Adjacent sequences: A321949 A321950 A321951 * A321953 A321954 A321955

Keyword

nonn

Author

Alois P. Heinz, Nov 22 2018

Status

approved