OFFSET
1,2
EXAMPLE
a(4) = 4 because 609*10^4-1 = 6089999, a prime.
PROG
(PARI) is(n)=ispseudoprime(609*10^n-1) \\ Charles R Greathouse IV, Jun 13 2017
CROSSREFS
KEYWORD
more,nonn
AUTHOR
Jason Earls, Jun 30 2005
EXTENSIONS
a(27) from Michael S. Branicky, May 19 2023
a(28)-a(31) from Michael S. Branicky, Oct 29 2024
STATUS
approved