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Search: id:A091288
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A091288 Integer solutions x to (q=sigma[x]+sigma[x+1])/sigma[x+x+1], such that q=1, i.e. sigma[x]+sigma[x+1])=sigma[2x+1];sigma[]=A000203. +0
2
1, 4, 646, 1096, 16174, 22891, 64672, 353110, 468970, 515698, 733570, 1317343, 1633213, 1735288, 2026945, 2093506, 2709542, 4413772, 5005825, 5346241, 5388154 (list; graph; listen)
OFFSET

1,2

MATHEMATICA

Do[s=(DivisorSigma[1, n]+DivisorSigma[1, n+1])/ DivisorSigma[1, 2*n+1]; If[Equal[s, 1], Print[n]], {n, 1, 10000000}]

CROSSREFS

Cf. A000203, A091287-A091290.

Adjacent sequences: A091285 A091286 A091287 this_sequence A091289 A091290 A091291

Sequence in context: A069641 A079103 A067171 this_sequence A046348 A114765 A059754

KEYWORD

nonn

AUTHOR

Labos E. (labos(AT)ana.sote.hu), Feb 16 2004

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Last modified May 16 23:01 EDT 2008. Contains 139884 sequences.


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