A181987 Numbers n such that (39^n - 1)/38 is prime.

349, 631, 4493, 16633, 36341

Offset: 1

Author

Robert Price, Apr 04 2012

Keywords

• hard
• more
• nonn

Links

• Harvey Dubner, Generalized repunit primes, Math. Comp., 61 (1993), 927-930.
• Henri Lifchitz, Mersenne and Fermat primes field

Crossrefs

Cf. A028491, A004061, A004062, A004063, A004023, A005808, A004064, A016054, A006032, A006033, A006034, A006035, A127995, A127996, A127997, A127998, A127999, A098438, A128002, A128003, A128004, A128005.

Programs

Mathematica

Select[Prime[Range[100000]], PrimeQ[(39^#-1)/38]&]

PARI

is(n)=ispseudoprime((39^n-1)/38) \\ Charles R Greathouse IV, Jun 13 2017