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Search: id:A091289
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| A091289 |
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Integer solutions x to (q=sigma[x]+sigma[x+1])/sigma[x+x+1], such that q=2 i.e. sigma[x]+sigma[x+1])=2*sigma[2x+1];sigma[]=A000203. |
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| 215, 923, 944, 1715, 2379, 5355, 38429, 87584, 110483, 212795, 291039, 1016519, 1051644, 1198139, 2729979, 9380447, 9397674, 31476500, 31749948, 33146259, 33497064, 47004099, 50482278, 52026408, 54114528, 61571795, 79000679
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OFFSET
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1,1
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MATHEMATICA
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Do[s=(DivisorSigma[1, n]+DivisorSigma[1, n+1])/ DivisorSigma[1, 2*n+1]; If[Equal[s, 2], Print[n]], {n, 1, 10000000}]
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CROSSREFS
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Cf. A000203, A091287-A091290.
Sequence in context: A043391 A063358 A137205 this_sequence A085754 A002239 A018863
Adjacent sequences: A091286 A091287 A091288 this_sequence A091290 A091291 A091292
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KEYWORD
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nonn
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu), Feb 16 2004
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EXTENSIONS
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a(16)-a(27) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Jan 31 2009
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