|
%I #15 Jul 14 2023 15:13:42
%S 2,30,74,122,386,476,630,20132
%N Numbers k such that 2*17^k - 1 is prime.
%C Is it true that a(n)= 0 or 2 (mod 6) and a(n)= 0 or 2 (mod 4)?
%C Yes. This can be proved mod 21. [_Charles R Greathouse IV_, Jul 31 2011]
%t Table[If[PrimeQ[2*17^m-1],m],{m,1,2000}]//Union
%o (PARI) forstep(n=2,1e4,[4,2],if(ispseudoprime(2*17^n-1),print1(n", "))) \\ _Charles R Greathouse IV_, Jul 31 2011
%K nonn,more
%O 1,1
%A _José María Grau Ribas_, Jul 17 2011
%E a(8) from _Michael S. Branicky_, Jul 14 2023
|
