OFFSET
1,2
MATHEMATICA
Do[ If[ Mod[ EulerPhi[ Prime[n] + 1], n] == 0, Print[n]], {n, 1, 10^7} ]
PROG
(PARI) isok(k) = (eulerphi(prime(k)+1) % k) == 0; \\ Michel Marcus, Feb 17 2021
CROSSREFS
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Feb 05 2002
EXTENSIONS
Edited and extended by Robert G. Wilson v, Feb 07 2002
STATUS
approved