A128004 Numbers n such that (38^n - 1)/37 is prime.

3, 7, 401, 449, 109037

Offset

1,1

Comments

No other terms < 100000. - Robert Price, Dec 23 2011

Links

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

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

H. Lifchitz, Mersenne and Fermat primes field

Index to primes in various ranges, form ((k+1)^n-1)/k

Mathematica

Select[Prime[Range[100]], PrimeQ[(38^#-1)/37]&]

Prog

(PARI) is(n)=ispseudoprime((38^n-1)/37) \\ Charles R Greathouse IV, Feb 17 2017

Crossrefs

Sequence in context: A248701 A103317 A104051 * A281889 A086559 A013426

Adjacent sequences: A128001 A128002 A128003 * A128005 A128006 A128007

Keyword

hard,more,nonn

Author

Alexander Adamchuk, Feb 11 2007

Extensions

a(5) corresponds to a probable prime discovered by Paul Bourdelais, Oct 17 2017

Status

approved