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A364081
Numbers k such that (20^k + 1)^2 - 2 is prime.
3
1, 15, 44, 77, 141, 208, 304, 1169, 3359, 5050, 22431, 34935, 92990
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
Cf. A091513 (b=2), A100902 (b=6), A100904 (b=10), A364077 (b=12), A100906 (b=14), A364079 (b=18), A100908 (b=22).
Cf. A364080.
Sequence in context: A133343 A027845 A201810 * A292018 A289669 A295980
KEYWORD
nonn,hard,more
AUTHOR
Jeppe Stig Nielsen, Jul 03 2023
STATUS
approved