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

1,1

Comments

Numbers n such that A255920(n) = 7.

Links

Table of n, a(n) for n=1..40.

Prog

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

Sequence in context: A208486 A242038 A045099 * A237445 A122421 A187992

Adjacent sequences: A325880 A325881 A325882 * A325884 A325885 A325886

Keyword

nonn

Author

Felix Fröhlich, May 26 2019

Status

approved