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A307643
Number of partitions of n^3 into exactly n positive cubes.
4
1, 1, 0, 0, 0, 0, 1, 0, 2, 6, 14, 23, 51, 108, 228, 511, 1158, 2500, 5603, 12304, 26969, 59222, 130115, 285370, 624965, 1368603, 2987117, 6517822, 14187920, 30823278, 66834822, 144671698, 312551894, 673913968, 1450292087, 3114720013, 6676277754, 14281662079
OFFSET
0,9
FORMULA
a(n) = A320841(n^3,n).
EXAMPLE
9^3 =
1^3 + 1^3 + 1^3 + 2^3 + 3^3 + 3^3 + 3^3 + 5^3 + 8^3 =
1^3 + 1^3 + 2^3 + 4^3 + 4^3 + 5^3 + 5^3 + 5^3 + 6^3 =
1^3 + 1^3 + 4^3 + 4^3 + 4^3 + 4^3 + 4^3 + 4^3 + 7^3 =
1^3 + 2^3 + 2^3 + 3^3 + 4^3 + 4^3 + 5^3 + 6^3 + 6^3 =
1^3 + 3^3 + 3^3 + 3^3 + 3^3 + 3^3 + 5^3 + 5^3 + 7^3 =
2^3 + 3^3 + 3^3 + 3^3 + 3^3 + 3^3 + 3^3 + 6^3 + 7^3,
so a(9) = 6.
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^3, n$2):
seq(a(n), n=0..25); # Alois P. Heinz, Oct 12 2019
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^3, n, n];
a /@ Range[0, 25] (* Jean-François Alcover, Nov 07 2020, after Alois P. Heinz *)
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Apr 19 2019
EXTENSIONS
More terms from Vaclav Kotesovec, Apr 20 2019
STATUS
approved