OFFSET
1,1
COMMENTS
This sequence is infinite. For example, 3*4^k is a term for all k > 0, since core(3*4^k) = 3, phi(3*4^k) = 4^k and 4^k == 1 (mod 3). - Amiram Eldar, Sep 03 2020
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
MATHEMATICA
core[n_] := Times @@ (First[#]^Mod[Last[#], 2] & /@ FactorInteger[n]); Select[Range[10^4], Mod[EulerPhi[#], core[#]] == 1 &] (* Amiram Eldar, Sep 03 2020 *)
PROG
(PARI) for(n=1, 15000, if(eulerphi(n)%core(n)==1, print1(n, ", ")))
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Benoit Cloitre, Apr 27 2002
EXTENSIONS
Name corrected by Amiram Eldar, Sep 05 2020
STATUS
approved