A255205 Primes p for which exactly two bases b with 1 < b < p exist such that p is a base b Wieferich prime.

11, 71, 127, 131, 163, 211, 229, 313, 347, 349, 353, 359, 367, 463, 509, 599, 607, 631, 647, 673, 797, 827, 829, 977, 1021, 1061, 1087, 1109, 1123, 1187, 1327, 1381, 1399, 1429, 1453, 1483, 1493, 1499, 1523, 1531, 1549, 1553, 1607, 1613, 1619, 1621, 1657, 1669

Offset: 1

Author

Felix Fröhlich, Feb 17 2015

Keywords

• nonn

Comments

p = prime(n) such that A242830(n) = 2.

Crossrefs

Cf. A255203, A255204, A255206, 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==2, print1(p, ", ")))