OFFSET
1,1
COMMENTS
Conjecture: the sequence is infinite.
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
MATHEMATICA
Select[Prime[Range[25]], Divisible[3^# - 3, # - 3] &] (* Alonso del Arte, Apr 17 2018 *)
Select[Range[10^5], # != 3 && PrimeQ[#] && PowerMod[3, #, # - 3] == Mod[3, # - 3] &] (* Amiram Eldar, Apr 06 2021 *)
PROG
(PARI) isok(p) = isprime(p) && (p != 3) && (Mod(3, p-3)^p == Mod(3, p-3)); \\ Michel Marcus, Apr 17 2018
CROSSREFS
KEYWORD
nonn
AUTHOR
Alex Ratushnyak, Apr 17 2018
STATUS
approved