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

349, 631, 4493, 16633, 36341

Offset

1,1

Links

Table of n, a(n) for n=1..5.

Harvey Dubner, Generalized repunit primes, Math. Comp., 61 (1993), 927-930.

Henri Lifchitz, Mersenne and Fermat primes field

Mathematica

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

Prog

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

Crossrefs

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

Sequence in context: A230609 A177174 A139658 * A054824 A031420 A273530

Adjacent sequences: A181984 A181985 A181986 * A181988 A181989 A181990

Keyword

hard,more,nonn

Author

Robert Price, Apr 04 2012

Status

approved