A255206 Primes p for which exactly three bases b with 1 < b < p exist such that p is a base b Wieferich prime.

269, 331, 571, 863, 883, 907, 1097, 1103, 1291, 1579, 1697, 1741, 2179, 2213, 2221, 2281, 2309, 2311, 2551, 2671, 2677, 2693, 2707, 2789, 2791, 3191, 3253, 3571, 3617, 3877, 3931, 4049, 4787, 4813, 4987, 5021, 5153, 5197, 5227, 5347, 5519, 5669, 5689, 5693

Offset: 1

Author

Felix Fröhlich, Feb 17 2015

Keywords

• nonn

Comments

p = prime(n) such that A242830(n) = 3.

Crossrefs

Cf. A255203, A255204, A255205, A255207, A255208, A255209, A255210.

Programs

PARI

forprime(p=1, , b=2; i=0; while(b < p, if(Mod(b, p^2)^(p-1)==1, i++); b++); if(i==3, print1(p, ", ")))