OFFSET
1,2
COMMENTS
Such primes are sometimes called Kynea primes of base 20.
LINKS
Prime-Wiki, Carol-Kynea prime.
Eric Weisstein's World of Mathematics, Near-Square Prime.
PROG
(PARI) for(k=1, 1200, ispseudoprime((20^k+1)^2-2)&&print1(k, ", "))
CROSSREFS
KEYWORD
nonn,hard,more
AUTHOR
Jeppe Stig Nielsen, Jul 03 2023
STATUS
approved