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A255206
Primes p for which exactly three bases b with 1 < b < p exist such that p is a base b Wieferich prime.
8
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
1,1
COMMENTS
p = prime(n) such that A242830(n) = 3.
PROG
(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, ", ")))
KEYWORD
nonn
AUTHOR
Felix Fröhlich, Feb 17 2015
STATUS
approved