cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A074241 Numbers n such that phi(n+1) = reverse(phi(n)).

Original entry on oeis.org

1, 3, 15, 129, 833, 5044, 59815, 267335, 297863, 9633693, 4642779313, 62935243460, 91770096041, 1648209018135
Offset: 1

Views

Author

Joseph L. Pe, Sep 18 2002

Keywords

Comments

a(15) > 2*10^12. - Giovanni Resta, Aug 12 2019

Examples

			phi(129 + 1) = 48 = reverse(84) = reverse(phi(129)), so 129 is a term of the sequence.

Crossrefs

Cf. A004086, A075475.

Programs

  • Mathematica
    Select[Range[10^5], FromDigits[Reverse[IntegerDigits[EulerPhi[ # ]]]] == EulerPhi[ # + 1] &]
  • PARI
    isok(n) = eulerphi(n+1) == fromdigits(Vecrev(digits(eulerphi(n)))); \\ Michel Marcus, Aug 12 2019

Extensions

a(8)-a(14) from Giovanni Resta, Aug 12 2019
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Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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