OFFSET
1,1
COMMENTS
a(8) > 10^5. - Robert Price, Apr 12 2014
LINKS
H. Dubner, Generalized repunit primes, Math. Comp., 61 (1993), 927-930.
H. Lifchitz, Mersenne and Fermat primes field
MAPLE
A240765:=n->`if`(isprime((43^n - 1)/42), n, NULL); seq(A240765(n), n=1..100000); # Wesley Ivan Hurt, Apr 12 2014
MATHEMATICA
Select[Prime[Range[100000]], PrimeQ[(43^#-1)/42]&]
PROG
(PARI) is(n)=ispseudoprime((43^n-1)/42) \\ Charles R Greathouse IV, Feb 20 2017
CROSSREFS
KEYWORD
hard,more,nonn
AUTHOR
Robert Price, Apr 12 2014
EXTENSIONS
a(8) from Paul Bourdelais, Aug 04 2020
STATUS
approved