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Search: id:A110817
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| A110817 |
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Numbers n such that (1/n)sigma(n+1) is an integer. |
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+0
1
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OFFSET
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1,2
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COMMENT
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These are all the terms up to 10^8.
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EXAMPLE
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sigma(2+1)/2 = 2, so 2 is a term of the sequence.
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MATHEMATICA
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Select[Range[10^6], IntegerQ[DivisorSigma[1, # + 1]/# ] &]
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CROSSREFS
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Sequence in context: A047684 A162955 A064448 this_sequence A110860 A050995 A117116
Adjacent sequences: A110814 A110815 A110816 this_sequence A110818 A110819 A110820
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KEYWORD
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nonn
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AUTHOR
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Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Sep 15 2005
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EXTENSIONS
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a(6) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Nov 15 2009
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