OFFSET
1,1
COMMENTS
All terms of this sequence are odd. - Saish S. Kambali, Aug 16 2023
MATHEMATICA
primeQ[n_] := n > 0 && PrimeQ[n]; Select[Range[1, 350, 2], primeQ[2*EulerPhi[#] - #] &] (* Amiram Eldar, Aug 16 2023 *)
PROG
(Python)
from sympy import totient, isprime
print([n for n in range(1, 340) if isprime(2 * totient(n) - n)])
(PARI) isok(k) = isprime(2*eulerphi(k)-k); \\ Michel Marcus, Sep 13 2023
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Darío Clavijo, Aug 16 2023
STATUS
approved