A075475 Numbers n such that reverse(phi(n+1)) = phi(n).

1, 3, 15, 129, 270, 833, 5044, 59815, 9633693, 26427528, 4642779313, 26594615202, 62935243460, 91770096041, 1648209018135

Offset: 1

Author

Labos Elemer, Sep 20 2002

Keywords

• nonn
• base
• more

Comments

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

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

Examples

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

Crossrefs

Cf. A004086, A069225, A074241, A074242.

Programs

Mathematica

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

PARI

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

Extensions

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

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