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Search: id:A156942
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| A156942 |
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Odd numbers whose abundancy is odd. |
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+0
2
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| 11025, 99225, 245025, 275625, 342225, 540225, 893025, 1334025, 1863225, 2205225, 2480625, 3080025, 3186225, 3980025, 4601025, 4862025, 5832225, 6125625, 6890625, 7868025, 8037225, 8555625, 9272025, 9828225, 10595025, 10989225
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Number of terms <10^n: 0, 0, 0, 0, 2, 7, 24, 83, 250, 792, 2484, 7988, 25383, 80082, ..., . Not all are a multiple of 25, i.e.; 81162081= 9009^2 = (9*7*11*13)^2. See A156943. Conjecture: n must be an odd square.
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LINKS
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R. G. Wilson v, Table of n, a(n) for n=1,...,1000
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MATHEMATICA
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f[n_] := DivisorSigma[1, n] - 2 n; Select[ Range[1, 12006223, 2], f@# > 0 &]
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CROSSREFS
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Cf. A156903, A156943.
Sequence in context: A096930 A160711 A129087 this_sequence A164518 A139409 A032427
Adjacent sequences: A156939 A156940 A156941 this_sequence A156943 A156944 A156945
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KEYWORD
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nonn
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AUTHOR
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Robert G. Wilson v (rgwv(AT)rgwv.com), Feb 18 2009
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