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Search: id:A116902
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| A116902 |
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Number of partitions of n into at least two parts such that the product of largest and smallest part exceeds n. |
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+0
3
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| 0, 0, 0, 0, 1, 2, 2, 3, 4, 6, 8, 10, 13, 16, 20, 23, 32, 36, 46, 55, 66, 78, 99, 108, 136, 160, 188, 216, 271, 296, 364, 415, 484, 559, 684, 725, 890, 1028, 1175, 1313, 1599, 1727, 2084, 2335, 2636, 3019, 3620, 3801, 4553, 5170, 5819, 6460, 7690, 8265, 9728, 10783
(list; graph; listen)
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OFFSET
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1,6
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EXAMPLE
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a(9)=4 since property holds for 4 partitions of 9: {7,2}, {6,3}, {5,4}, {5,2,2}.
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MATHEMATICA
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<< DiscreteMath`Combinatorica`; fun[n_]:=Select[Partitions[n], (Length[ # ]>1 && Last[ # ]First[ # ]>n)&]; Table[Length[fun[k]], {k, 40}]
(* first do *) Needs["DiscreteMath`Combinatorica`] (* then *) f[n_] := Length@ Select[ Partitions@n, Length@# > 1 && Last@# First@# > n &]; Array[f, 56] - from Robert G. Wilson v (rgwv(at)rgwv.com), Apr 06 2006
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CROSSREFS
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Cf. A000041, A116900, A116901.
Sequence in context: A114541 A077114 A118246 this_sequence A066447 A035542 A130081
Adjacent sequences: A116899 A116900 A116901 this_sequence A116903 A116904 A116905
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KEYWORD
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nonn
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AUTHOR
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Giovanni Resta (g.resta(AT)iit.cnr.it), Mar 14 2006
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EXTENSIONS
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More terms from Robert G. Wilson v (rgwv(at)rgwv.com), Apr 06 2006
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