Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #13 Sep 08 2022 08:46:15
%S 0,1,4,5,12,16,27,87,252,1052,1691,3237,3669,16140,17072,27932,70811
%N Numbers n such that 7^n + 6^(n + 1) is prime.
%C a(18) > 10^5.
%t Select[Range[0,100000], PrimeQ[7^# + 6^(# + 1)] &]
%o (Magma) [n: n in [0..500] | IsPrime(7^n+6^(n+1))]; // _Vincenzo Librandi_, Jul 12 2016
%o (PARI) is(n)=ispseudoprime(7^n+6^(n+1)) \\ _Charles R Greathouse IV_, Jun 13 2017
%Y Cf. A093765.
%K nonn,more
%O 1,3
%A _Robert Price_, Jul 11 2016