

A275998


Numbers n such that phi(n^21) = phi(n^2+1).


0




OFFSET

1,1


COMMENTS

No other terms below 10^8.  Michel Marcus, Aug 17 2016


LINKS

Table of n, a(n) for n=1..4.


EXAMPLE

3 is a term because phi(3^21) = phi(3^2+1).


MATHEMATICA

Select[Range@10000000, EulerPhi@(#^2  1) == EulerPhi[#^2 + 1] &] (* Vincenzo Librandi, Aug 18 2016 *)


PROG

(PARI) isok(n) = eulerphi(n^21) == eulerphi(n^2+1); \\ Michel Marcus, Aug 16 2016
(MAGMA) [n: n in [2..100000]  EulerPhi(n^21) eq EulerPhi(n^2+1)]; // Vincenzo Librandi, Aug 18 2016


CROSSREFS

Cf. A000010, A066812.
Sequence in context: A279658 A026294 A199688 * A098401 A011544 A127503
Adjacent sequences: A275995 A275996 A275997 * A275999 A276000 A276001


KEYWORD

nonn,more


AUTHOR

Altug Alkan, Aug 16 2016


STATUS

approved



