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Search: id:A126111
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| A126111 |
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Number of subsets of {1,2,3,...,n} whose sum is a cube. |
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+0
1
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| 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
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OFFSET
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1,1
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EXAMPLE
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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.
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MATHEMATICA
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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] (*Chandler*)
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CROSSREFS
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Cf. Number of subsets of {1, 2, 3, ..., n} whose sum is a square/prime in A126024, A127542.
Sequence in context: A035658 A077018 A007918 this_sequence A122789 A014208 A059690
Adjacent sequences: A126108 A126109 A126110 this_sequence A126112 A126113 A126114
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KEYWORD
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nonn
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AUTHOR
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Zak Seidov (zakseidov(AT)gmail.com), Mar 05 2007
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EXTENSIONS
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Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Mar 07 2007
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