OFFSET
1,3
COMMENTS
a(20) > 21059. - Jinyuan Wang, Dec 08 2019
MATHEMATICA
Do[ If[ PrimeQ[ 2*7^n + 3 ], Print[n] ], {n, 1, 6000} ]
PROG
(PARI) is(n)=ispseudoprime(2*7^n+3) \\ Charles R Greathouse IV, Jun 13 2017
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Robert G. Wilson v, Feb 12 2001
EXTENSIONS
a(18)-a(19) from Jinyuan Wang, Dec 08 2019
a(20)-a(21) from Michael S. Branicky, Jul 09 2024
STATUS
approved