A071382 Numbers n such that (30^n+1)/31 is a prime.

139, 173, 547, 829, 2087, 2719, 3109, 10159, 56543, 80599

Offset: 1

Author

Rick L. Shepherd, May 22 2002

Keywords

• nonn
• more

Comments

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

a(11) > 10^5. - Robert Price, Jul 10 2013

Links

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

Crossrefs

Cf. A071381.

Programs

Mathematica

 Select[Range[3000], PrimeQ[(30^# + 1) / 31] &] (* Vincenzo Librandi, Oct 29 2017 *)

PARI

isok(n) = (denominator(p=(30^n+1)/31)==1) && isprime(p); \\ Michel Marcus, Oct 29 2017

Extensions

a(8) from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 05 2008

a(9)-a(10) from Robert Price, Jul 10 2013