The OEIS is supported by the many generous donors to the OEIS Foundation.
%I #26 Sep 08 2022 08:46:03
%S 0,3,5,15,375,98003
%N Numbers k such that 7^k + k^7 + 1 is prime.
%C a(6) > 8000. - _Joerg Arndt_, Sep 29 2012
%C a(7) > 2*10^5. - _Robert Price_, Jun 15 2014
%t Select[Range[0, 5000], PrimeQ[7^# + #^7 + 1] &]
%o (Magma) [n: n in [0..400] | IsPrime(7^n + n^7 + 1)]
%o (PARI) is(n)=ispseudoprime(7^n+n^7+1) \\ _Charles R Greathouse IV_, Jun 06 2017
%Y Cf. A100357, A215441, A216423, A215442, A243934.
%K nonn,hard,more
%O 1,2
%A _Vincenzo Librandi_, Sep 06 2012
%E a(6) from _Robert Price_, May 24 2014