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%I #14 Jun 13 2017 13:48:01
%S 3,5,7,11,17,19,41,53,109,167,2207,3623,5059,5471,7949,21211,32993,
%T 60251
%N Numbers n such that (9^n + 4^n)/13 is prime.
%C All terms are prime.
%C The next element, a(19), is greater than 10^5.
%t Select[ Prime[ Range[1, 100000] ], PrimeQ[ (9^# + 4^#)/13 ]& ]
%o (PARI) is(n)=ispseudoprime((9^n+4^n)/13) \\ _Charles R Greathouse IV_, Jun 13 2017
%Y cf. A181141, A128339, A057175, A125956, A187819.
%K more,nonn
%O 1,1
%A _Robert Price_, Feb 09 2013
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