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Search: id:A074242
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| A074242 |
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Numbers n such that sigma(n+1) = reverse(sigma(n)). |
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+0
2
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OFFSET
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1,1
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COMMENT
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These are all the terms < 10^7.
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EXAMPLE
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sigma(5602 + 1) = 6048 = reverse(8406) = reverse(sigma(5602)), so 5602 is a term of the sequence.
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MATHEMATICA
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Do[ If[FromDigits[Reverse[IntegerDigits[DivisorSigma[1, n]]]] == DivisorSigma[1, n + 1], Print[n]], {n, 1, 10^7}]
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CROSSREFS
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Sequence in context: A109565 A126784 A071813 this_sequence A032737 A058003 A014799
Adjacent sequences: A074239 A074240 A074241 this_sequence A074243 A074244 A074245
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KEYWORD
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base,more,nonn,bref
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AUTHOR
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Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Sep 19 2002
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EXTENSIONS
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a(3)-a(4) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Feb 01 2009
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