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A075475 Numbers n such that reverse(phi(n+1)) = phi(n). 1
1, 3, 15, 129, 270, 833, 5044, 59815, 9633693, 26427528, 4642779313, 26594615202, 62935243460, 91770096041, 1648209018135 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(12) > 25*10^9. - Donovan Johnson, Jun 09 2011

a(16) > 2*10^12. - Giovanni Resta, Aug 12 2019

LINKS

Table of n, a(n) for n=1..15.

EXAMPLE

n=59815: phi(n) = 40992, phi(n+1) = 29904 = rev(phi(n)).

MATHEMATICA

Select[Range[60000], IntegerReverse[EulerPhi[# + 1]] == EulerPhi[#] &] (* Giovanni Resta, Aug 12 2019 *)

PROG

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

CROSSREFS

Cf. A004086, A069225, A074241, A074242.

Sequence in context: A182489 A330804 A335390 * A074241 A228365 A117694

Adjacent sequences:  A075472 A075473 A075474 * A075476 A075477 A075478

KEYWORD

nonn,base,more

AUTHOR

Labos Elemer, Sep 20 2002

EXTENSIONS

a(9)-a(11) from Donovan Johnson, Jun 09 2011

a(12)-a(15) from Giovanni Resta, Aug 12 2019

STATUS

approved

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Last modified May 8 23:53 EDT 2021. Contains 343685 sequences. (Running on oeis4.)