A126111 Number of subsets of {1,2,3,...,n} whose sum is a cube.

2, 2, 2, 3, 5, 6, 8, 15, 29, 48, 71, 112, 216, 445, 849, 1459, 2403, 4239, 8343, 17049, 33416, 61192, 107290, 190803, 361136, 722568, 1457638, 2847209, 5322619, 9679593, 17715193, 33626815, 66430582, 133432610, 264832126, 511136916, 960634698, 1786150886

Offset

1,1

Links

Alois P. Heinz, Table of n, a(n) for n = 1..300

Example

There are five subsets of {1,2,3,4,5} that sum to a cube: {}, {1},{3,5}, {1,2,5} and {1,3,4}. Thus a(5)=5.

Mathematica

g[n_] := Block[{p = Product[1 + z^i, {i, n}]}, Sum[Boole[IntegerQ[k^(1/3)]]*Coefficient[p, z, k], {k, 0, n*(n + 1)/2}]]; Array[g, 37] (* Ray Chandler, Mar 07 2007 *)

Crossrefs

Cf. number of subsets of {1,2,3,...,n} whose sum is a square/prime in A126024, A127542.

Sequence in context: A278167 A239470 A320786 * A100142 A296103 A247907

Adjacent sequences: A126108 A126109 A126110 * A126112 A126113 A126114

Keyword

nonn

Author

Zak Seidov, Mar 05 2007

Extensions

Extended by Ray Chandler, Mar 07 2007

More terms from Alois P. Heinz, Jan 18 2014

Status

approved