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%I #14 Sep 21 2024 12:21:36
%S 0,19,59,291,327,3951,18163
%N Numbers k such that 1 + 20^k + 200^k is prime.
%C No more terms up to k = 6900.
%o (PARI) is(n)=ispseudoprime(1+20^n+200^n) \\ _Charles R Greathouse IV_, Jun 13 2017
%K nonn,more
%O 1,2
%A _Jason Earls_, Dec 06 2009
%E Offset changed by _Andrew Howroyd_, Sep 18 2024
%E a(7) from _Michael S. Branicky_, Sep 21 2024