login
Numbers k such that 19^k + k^19 - 1 is prime.
1

%I #14 Jul 12 2018 11:36:46

%S 1,17,145,427,4327,14195

%N Numbers k such that 19^k + k^19 - 1 is prime.

%C a(7) > 10^5. - _Robert Price_, Mar 25 2014

%t Select[Range[0, 5000], PrimeQ[19^# + #^19 - 1] &]

%o (PARI) is(n)=ispseudoprime(19^n+n^19-1) \\ _Charles R Greathouse IV_, Jun 13 2017

%Y Cf. A100357, A215434-A215446, A216375.

%K nonn,hard,more

%O 1,2

%A _Vincenzo Librandi_, Sep 07 2012

%E a(6) from _Robert Price_, Mar 25 2014