A331899 Number of compositions (ordered partitions) of n^3 into distinct cubes.
1, 1, 1, 1, 1, 1, 7, 1, 1, 127, 1, 1, 127, 769, 10945, 15961, 86641, 86521, 430717, 4140367, 4146751, 93669001, 1538834041, 663998665, 6883029151, 1014140647, 20591858857, 121532206567, 1637261351983, 2981530899847, 5950338797191, 47072230385425
Offset: 0
Keywords
Examples
a(6) = 7 because we have [216], [125, 64, 27], [125, 27, 64], [64, 125, 27], [64, 27, 125], [27, 125, 64] and [27, 64, 125].
Links
Programs
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Maple
b:= proc(n, i, p) option remember; `if`((i*(i+1)/2)^2
n, 0, b(n-i^3, i-1, p+1))+b(n, i-1, p))) end: a:= n-> b(n^3, n, 0): seq(a(n), n=0..33); # Alois P. Heinz, Jan 31 2020 -
Mathematica
b[n_, i_, p_] := b[n, i, p] = If[(i(i+1)/2)^2 < n, 0, If[n == 0, p!, If[i^3 > n, 0, b[n - i^3, i - 1, p + 1]] + b[n, i - 1, p]]]; a[n_] := b[n^3, n, 0]; a /@ Range[0, 33] (* Jean-François Alcover, Nov 26 2020, after Alois P. Heinz *)