A057188 Numbers n such that (22^n+1)/23 is a prime.

3, 5, 13, 43, 79, 101, 107, 227, 353, 7393, 50287

Offset: 1

Author

N. J. A. Sloane, Sep 15 2000

Keywords

• nonn
• more

Comments

Some of the larger terms may only correspond to probable primes.

a(12) > 10^5 - Robert Price, Jun 02 2013

Links

• H. Dubner and T. Granlund, Primes of the Form (b^n+1)/(b+1), J. Integer Sequences, 3 (2000), #P00.2.7.

Programs

PARI

isok(n) = (denominator(p=(22^n+1)/23)==1) && isprime(p); \\ Michel Marcus, Oct 30 2017

Extensions

a(11) from Robert Price, Jun 02 2013