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A074241 Numbers n such that phi(n+1) = reverse(phi(n)). 1
1, 3, 15, 129, 833, 5044, 59815, 267335, 297863, 9633693, 4642779313, 62935243460, 91770096041, 1648209018135 (list; graph; refs; listen; history; text; internal format)
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

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Last modified June 25 12:30 EDT 2022. Contains 354851 sequences. (Running on oeis4.)