A249330 Primes which do not divide any repunit number R(p) = (10^p - 1)/9 with p prime.

2, 5, 7, 13, 17, 19, 23, 29, 31, 43, 47, 59, 61, 67, 71, 73, 89, 97, 101, 103, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 179, 181, 191, 193, 197, 199, 211, 223, 229, 233, 241, 251, 257, 263, 269, 277, 281, 283, 293, 307, 311, 313, 331, 337, 349, 353

Offset: 1

Author

Arkadiusz Wesolowski, Oct 25 2014

Keywords

• nonn
• base

Comments

If a prime p has period n, then p divides 10^m - 1 for all m divisible by n. Therefore the sequence together with 3 is the complement in the primes of A072859.

Crossrefs

Cf. A072859.

Programs

Magma

[2] cat [p: p in PrimesInInterval(5, 353) | not IsPrime(Modorder(10, p))];