OFFSET
1,1
LINKS
Giovanni Resta, Table of n, a(n) for n = 1..479 (terms < 10^15, first 75 terms from Felix Fröhlich)
MATHEMATICA
Select[Range[167*10^5], PowerMod[5, EulerPhi[#], #^2]==1&] (* Harvey P. Dale, Jun 02 2020 *)
PROG
(PARI) for(n=2, 10^9, if(Mod(5, n^2)^(eulerphi(n))==1, print1(n, ", ")))
CROSSREFS
KEYWORD
nonn
AUTHOR
Felix Fröhlich, May 27 2014
STATUS
approved