

A128005


Numbers n such that (40^n  1)/39 is prime.


11




OFFSET

1,1


COMMENTS

No other terms for n < 100000.  Robert Price, Jan 27 2012


LINKS

Table of n, a(n) for n=1..9.
H. Dubner, Generalized repunit primes, Math. Comp., 61 (1993), 927930.
H. Lifchitz, Mersenne and Fermat primes field
Index to primes in various ranges, form ((k+1)^n1)/k


MATHEMATICA

Select[Prime[Range[100]], PrimeQ[(40^#1)/39]&]


PROG

(PARI) isok(n) = isprime((40^n1)/39); \\ Michel Marcus, Mar 13 2016


CROSSREFS

Sequence in context: A097052 A102937 A045358 * A045359 A042809 A002531
Adjacent sequences: A128002 A128003 A128004 * A128006 A128007 A128008


KEYWORD

hard,more,nonn


AUTHOR

Alexander Adamchuk, Feb 11 2007


EXTENSIONS

More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 05 2008


STATUS

approved



