A255922 Bases b for which exactly one Wieferich prime p with p < b exists such that p is a base-b Wieferich prime.

5, 7, 8, 9, 10, 13, 21, 22, 23, 24, 25, 27, 29, 30, 31, 32, 33, 35, 38, 42, 43, 44, 45, 46, 48, 50, 54, 55, 60, 61, 64, 70, 74, 77, 78, 79, 85, 91, 94, 98, 100, 105, 110, 112, 113, 115, 120, 122, 126, 128, 131, 132, 133, 136, 138, 141, 150, 151, 152, 153, 154

Offset

1,1

Comments

Numbers b such that A255920(n) = 1.

Links

Felix Fröhlich, Table of n, a(n) for n = 1..10000

Prog

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

Crossrefs

Cf. A255920.

Cf. bases b with exactly k base-b Wieferich primes less than b: A255921 (k=0), A255923 (k=2), A255924 (k=3), A255925 (k=4), A325881 (k=5), A325882 (k=6), A325883 (k=7), A325884 (k=8), A325885 (k=9), A325886 (k=10).

Sequence in context: A261917 A111339 A273786 * A241028 A171097 A166460

Adjacent sequences: A255919 A255920 A255921 * A255923 A255924 A255925

Keyword

nonn

Author

Felix Fröhlich, Mar 12 2015

Status

approved