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

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

Offset

1,2

Comments

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

Links

Table of n, a(n) for n=1..14.

Example

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

Mathematica

Select[Range[10^5], FromDigits[Reverse[IntegerDigits[EulerPhi[ # ]]]] == EulerPhi[ # + 1] &]

Prog

(PARI) isok(n) = eulerphi(n+1) == fromdigits(Vecrev(digits(eulerphi(n)))); \\ Michel Marcus, Aug 12 2019

Crossrefs

Cf. A004086, A075475.

Sequence in context: A330804 A335390 A075475 * A228365 A117694 A264795

Adjacent sequences: A074238 A074239 A074240 * A074242 A074243 A074244

Keyword

nonn,base,more

Author

Joseph L. Pe, Sep 18 2002

Extensions

a(8)-a(14) from Giovanni Resta, Aug 12 2019

Status

approved