OFFSET
1,1
COMMENTS
A068535 includes all powers of 2. a(3) = 1093 and a(7) = 3511 are the only known primes in this sequence. They belong to A001220 = Wieferich primes p: p^2 divides 2^(p-1) - 1. Note that most listed terms of this sequence are the multiples of Wieferich primes 1093 and 3511. No more terms in this sequence up to 6*10^6.
MATHEMATICA
Do[f=PowerMod[2, n, n]; g=PowerMod[2, n, n^2]; If[f==g&&!IntegerQ[Log[2, n]], Print[n]], {n, 1, 6000000}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Alexander Adamchuk, Dec 07 2006
EXTENSIONS
More terms from Amiram Eldar, Jun 19 2022
STATUS
approved