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%I #8 Jun 13 2017 14:26:02
%S 3,5,19,41,47,8231,33931,43781,50833,53719,67211
%N Numbers n such that (7^n + 4^n)/11 is prime.
%C All terms are primes.
%C a(11) > 10^5
%t Do[ p=Prime[n]; f=(7^p+4^p)/11; If[ PrimeQ[f], Print[p]], {n, 1, 9592} ]
%o (PARI) is(n)=ispseudoprime((7^n+4^n)/11) \\ _Charles R Greathouse IV_, Jun 13 2017
%Y Cf. A128335, A128067, A128337.
%K hard,more,nonn
%O 1,1
%A _Robert Price_, Oct 27 2012
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