A325883 Bases b where exactly seven primes p with p < b exist such that p is a base-b Wieferich prime.

1451, 1482, 3145, 3147, 3277, 3365, 3376, 4339, 4357, 4365, 4393, 4625, 5649, 5850, 7282, 7624, 8641, 8956, 8957, 9149, 9449, 10040, 10093, 10538, 10835, 10889, 12001, 12476, 12907, 13253, 14005, 14027, 14032, 14500, 15029, 15229, 15797, 15857, 16249, 16757

Offset: 1

Author

Felix Fröhlich, May 26 2019

Keywords

• nonn

Comments

Numbers n such that A255920(n) = 7.

Crossrefs

Cf. A255920.

Cf. bases b with exactly k base-b Wieferich primes less than b: A255921 (k=0), A255922 (k=1), A255923 (k=2), A255924 (k=3), A255925 (k=4), A325881 (k=5), A325882 (k=6), A325884 (k=8), A325885 (k=9), A325886 (k=10).

Programs

PARI

is(n) = my(i=0); forprime(p=1, n-1, if(Mod(n, p^2)^(p-1)==1, i++)); i==7