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 A074242 Numbers n such that sigma(n+1) = reverse(sigma(n)). 1
 5602, 42346, 184650339, 356930335, 453038125082 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS a(6) > 10^13. - Giovanni Resta, Jun 26 2015 LINKS EXAMPLE sigma(5602 + 1) = 6048 = reverse(8406) = reverse(sigma(5602)), so 5602 is a term of the sequence. MATHEMATICA Do[ If[FromDigits[Reverse[IntegerDigits[DivisorSigma[1, n]]]] == DivisorSigma[1, n + 1], Print[n]], {n, 1, 10^7}] PROG (PARI) isok(n) = digits(sigma(n+1)) == Vecrev(digits(sigma(n))); \\ Michel Marcus, Jun 26 2015 CROSSREFS Cf. A028980 (sigma(n) = reverse(sigma(n))). Sequence in context: A109565 A126784 A071813 * A032737 A237507 A198164 Adjacent sequences:  A074239 A074240 A074241 * A074243 A074244 A074245 KEYWORD base,more,nonn AUTHOR Joseph L. Pe, Sep 19 2002 EXTENSIONS a(3)-a(4) from Donovan Johnson, Feb 01 2009 a(5) from Giovanni Resta, Jun 26 2015 STATUS approved

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Last modified August 24 00:29 EDT 2017. Contains 291052 sequences.