A025460 Number of partitions of n into 7 positive cubes.

0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 1, 0, 0, 1, 0, 0, 0, 1, 1, 0, 1, 0, 0, 0, 1, 1, 0, 1, 0, 1, 0, 1, 1, 0, 0, 0, 1, 0, 1, 1, 0

Offset: 0

Author

David W. Wilson

Keywords

• nonn

Comments

The first term > 1 is a(131) = 2. - Michel Marcus, Apr 23 2019

Links

• Alois P. Heinz, Table of n, a(n) for n = 0..65536
• Index entries for sequences related to sums of cubes

Crossrefs

Column k=7 of A320841.

Programs

Maple

b:= proc(n, i, t) option remember; `if`(n=0, `if`(t=0, 1, 0),
      `if`(i<1 or t<1, 0, b(n, i-1, t)+
      `if`(i^3>n, 0, b(n-i^3, i, t-1))))
    end:
a:= n-> b(n, iroot(n, 3), 7):
seq(a(n), n=0..120);  # Alois P. Heinz, Dec 21 2018

Mathematica

b[n_, i_, t_] := b[n, i, t] = If[n == 0, If[t == 0, 1, 0], If[i < 1 || t < 1, 0, b[n, i - 1, t] + If[i^3 > n, 0, b[n - i^3, i, t - 1]]]];
a[n_] := b[n, n^(1/3) // Floor, 7];
a /@ Range[0, 120] (* Jean-François Alcover, Nov 23 2020, after Alois P. Heinz *)

Formula

a(n) = [x^n y^7] Product_{k>=1} 1/(1 - y*x^(k^3)). - Ilya Gutkovskiy, Apr 23 2019

Extensions

Second offset from Michel Marcus, Apr 23 2019