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A364080
Numbers k such that (20^k - 1)^2 - 2 is prime.
3
1, 2, 53, 183, 1281, 1300, 8041, 29936, 72820
OFFSET
1,2
COMMENTS
Such primes are sometimes called Carol 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
Cf. A091515 (b=2), A100901 (b=6), A100903 (b=10), A364076 (b=12), A100905 (b=14), A364078 (b=18), A100907 (b=22).
Cf. A364081.
Sequence in context: A249662 A249663 A130698 * A248988 A248989 A248990
KEYWORD
nonn,hard,more
AUTHOR
Jeppe Stig Nielsen, Jul 03 2023
STATUS
approved