A340977 Number of ways to write n as an ordered sum of 4 positive cubes.

1, 0, 0, 0, 0, 0, 0, 4, 0, 0, 0, 0, 0, 0, 6, 0, 0, 0, 0, 0, 0, 4, 0, 0, 0, 0, 4, 0, 1, 0, 0, 0, 0, 12, 0, 0, 0, 0, 0, 0, 12, 0, 0, 0, 0, 0, 0, 4, 0, 0, 0, 0, 6, 0, 0, 0, 0, 0, 0, 12, 0, 0, 0, 4, 0, 0, 6, 0, 0, 0, 12, 0, 0, 0, 0, 0, 0, 12, 4, 0, 0, 0, 0, 0, 4, 4, 0, 0, 0, 12, 0, 0, 0, 0, 0, 0, 24

Offset

4,8

Links

Robert Israel, Table of n, a(n) for n = 4..10000

Index entries for sequences related to sums of cubes

Formula

G.f.: (Sum_{k>=1} x^(k^3))^4.

Maple

b:= proc(n, t) option remember;
      `if`(n=0, `if`(t=0, 1, 0), `if`(t<1, 0, add((s->
      `if`(s>n, 0, b(n-s, t-1)))(j^3), j=1..iroot(n, 3))))
    end:
a:= n-> b(n, 4):
seq(a(n), n=4..100);  # Alois P. Heinz, Feb 01 2021

Mathematica

nmax = 100; CoefficientList[Series[Sum[x^(k^3), {k, 1, Floor[nmax^(1/3)] + 1}]^4, {x, 0, nmax}], x] // Drop[#, 4] &

Crossrefs

Cf. A000578, A010057, A025457, A051344, A173678, A280618, A340978, A340979, A340980, A340981, A340982, A340983.

Sequence in context: A308429 A308428 A308276 * A180989 A075444 A280492

Adjacent sequences: A340974 A340975 A340976 * A340978 A340979 A340980

Keyword

nonn

Author

Ilya Gutkovskiy, Feb 01 2021

Status

approved