OFFSET
1,1
COMMENTS
Primes p such that p-1 = phi(A001317(x)) has solution.
EXAMPLE
Prime 548898078721 is in the sequence because 548898078720 = phi(1095216660735) = phi(3*5*17*4294967297); all numbers 3, 5, 17 and 4294967297 are terms of A000215 (Fermat numbers).
PROG
(Magma) Set(Sort([EulerPhi(k)+1: k in [A001317(n)] | IsPrime(EulerPhi(k)+1)]))
CROSSREFS
KEYWORD
nonn
AUTHOR
Jaroslav Krizek, Nov 13 2016
EXTENSIONS
a(13) from Jinyuan Wang, Nov 01 2020
STATUS
approved