A364081 - OEIS

A364081

Numbers k such that (20^k + 1)^2 - 2 is prime.

1, 15, 44, 77, 141, 208, 304, 1169, 3359, 5050, 22431, 34935, 92990

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OFFSET

1,2

COMMENTS

Such primes are sometimes called Kynea primes of base 20.

LINKS

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).

KEYWORD

nonn,hard,more

AUTHOR

STATUS

approved