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%I #16 Apr 30 2023 02:01:14
%S 3,107,197,2843,3571,4451,31517
%N Numbers k such that (9^k + 7^k)/16 is prime.
%C All terms are prime.
%C The corresponding primes are 67, 79401467172644850007356716446663549450843749853576087044440771380676673442288169290888310265443988907, ...
%p select(n->isprime((9^n+7^n)/16),[seq(n,n=1..10000,2)]); # _Muniru A Asiru_, Mar 27 2018
%t Select[Range[1, 10000], PrimeQ[(9^n+7^n)/16] &]
%o (PARI) forprime(n=3, 10000, if(isprime((9^n+7^n)/16), print1(n, ", ")))
%o (Magma) [n: n in [1..10000] |IsPrime((9^n+7^n)/16)]
%Y Cf. A057175, A125956, A211409, A128339, A187819.
%K nonn,more,hard
%O 1,1
%A _Tim Johannes Ohrtmann_, Mar 19 2018
%E a(7) from _Michael S. Branicky_, Apr 29 2023
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