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Search: id:A076496
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| A076496 |
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Numbers n such that Mod[sigma[n],n]=12. |
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+0
3
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| 24, 30, 42, 54, 66, 78, 102, 114, 121, 138, 174, 186, 222, 246, 258, 282, 304, 318, 354, 366, 402, 426, 438, 474, 498, 534, 582, 606, 618, 642, 654, 678, 762, 780, 786, 822, 834, 894, 906, 942, 978, 1002, 1038, 1074, 1086, 1146, 1158, 1182, 1194, 1266, 1338
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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These numbers are also solutions of the equation: g[n]:=2n+1-sigma[n]=-11 (or they are cofacient numbers of type -11). - Vassil K. Tintschev (tinchev(AT)sunhe.jinr.ru), Dec 15 2004
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EXAMPLE
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6p is a solution if p>3 is prime, since sigma[6p]=1+2+3+6+p+2p+3p+6p=12(p+1)=2.6p+12=2n+12. These are "regular" solutions. Also n=121,304 are "singular" solutions. See other remainders in cross-references.
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MATHEMATICA
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Do[s=Mod[DivisorSigma[1, n], n]; If[IntegerQ[n/1000000], Print[{n}]]; If[Equal[s, 12], Print[{n, n/6}]], {n, 1, 1000}]
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CROSSREFS
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Cf. A045768-A045470, A076495.
Sequence in context: A111398 A030626 A125639 this_sequence A125640 A141545 A106682
Adjacent sequences: A076493 A076494 A076495 this_sequence A076497 A076498 A076499
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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), Oct 21 2002
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