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A074241
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Numbers n such that phi(n+1) = reverse(phi(n)).
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1
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1, 3, 15, 129, 833, 5044, 59815, 267335, 297863, 9633693, 4642779313, 62935243460, 91770096041, 1648209018135
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OFFSET
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1,2
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COMMENTS
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a(15) > 2*10^12. - Giovanni Resta, Aug 12 2019
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LINKS
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Table of n, a(n) for n=1..14.
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EXAMPLE
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phi(129 + 1) = 48 = reverse(84) = reverse(phi(129)), so 129 is a term of the sequence.
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MATHEMATICA
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Select[Range[10^5], FromDigits[Reverse[IntegerDigits[EulerPhi[ # ]]]] == EulerPhi[ # + 1] &]
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PROG
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(PARI) isok(n) = eulerphi(n+1) == fromdigits(Vecrev(digits(eulerphi(n)))); \\ Michel Marcus, Aug 12 2019
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CROSSREFS
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Cf. A004086, A075475.
Sequence in context: A330804 A335390 A075475 * A228365 A117694 A264795
Adjacent sequences: A074238 A074239 A074240 * A074242 A074243 A074244
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KEYWORD
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nonn,base,more
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AUTHOR
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Joseph L. Pe, Sep 18 2002
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EXTENSIONS
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a(8)-a(14) from Giovanni Resta, Aug 12 2019
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STATUS
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approved
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