OFFSET
1,2
MATHEMATICA
Select[Range[42000], Mod[EulerPhi[Prime[ # ] - 1], # ] == 0 &]
PROG
(PARI) for(k=1, 2600000, if(eulerphi(prime(k)-1)%k==0, print1(k, ", ")))
CROSSREFS
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Feb 05 2002
EXTENSIONS
More terms from Klaus Brockhaus, Feb 13 2002
More terms from Jinyuan Wang, Apr 05 2020
STATUS
approved