OFFSET
1,1
COMMENTS
The cyclic numbers satisfy phi(n)^phi(n) == gcd(n, phi(n))== 1 (mod n).
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..3238
MATHEMATICA
Select[Range[40000], PowerMod[EulerPhi[#], EulerPhi[#], #] > 1 && PowerMod[EulerPhi[#], EulerPhi[#], #] == GCD[#, EulerPhi[#]] &]
PROG
(PARI) is(n)=my(p=eulerphi(n), g=gcd(p, n)); g>1 && Mod(p, n)^p==g \\ Charles R Greathouse IV, Dec 27 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
José María Grau Ribas, Nov 01 2013
STATUS
approved