A128341 - OEIS

%I #14 Jun 11 2021 00:17:57

%S 3,5,13,347,977,1091,4861,4967,34679

%N Numbers k such that (12^k + 5^k)/17 is prime.

%C All terms are primes.

%C a(10) > 10^5. - _Robert Price_, May 05 2013

%t k=12; Do[p=Prime[n]; f=(k^p+5^p)/(k+5); If[ PrimeQ[f], Print[p] ], {n,1,100}]

%t Select[Range[1100],PrimeQ[(12^#+5^#)/17]&] (* _Harvey P. Dale_, Jul 24 2012 *)

%o (PARI) is(n)=isprime((12^n+5^n)/17) \\ _Charles R Greathouse IV_, Feb 17 2017

%Y Cf. A057171, A082387, A122853, A128335, A128336, A128337, A128338, A128339, A128340, A128342, A128343.

%Y Cf. A004061, A082182, A121877, A059802.

%Y Cf. A062572, A128344, A128345, A128346, A128347, A128348, A128349, A128350, A128351, A128352, A128353, A128354.

%K hard,more,nonn

%O 1,1

%A _Alexander Adamchuk_, Feb 27 2007

%E Two more terms (a(7) and a(8)) from _Harvey P. Dale_, Jul 24 2012

%E a(9) from _Robert Price_, May 05 2013