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Numbers n such that 2*11^n + 1 is prime.
3

%I #11 Oct 16 2015 04:39:42

%S 0,1,3,9,43,79,175,11325,13359,18577

%N Numbers n such that 2*11^n + 1 is prime.

%C a(11) > 2*10^5. - _Robert Price_, Oct 16 2015

%t Join[{0}, Select[Range[1, 175, 2], PrimeQ[2*11^# + 1] &]] (* _Arkadiusz Wesolowski_, Nov 06 2012 *)

%o (PARI) for(n=0, 1e5, if(isprime(2*11^n + 1), print1(n", "))) \\ _Altug Alkan_, Oct 16 2015

%Y Cf. A141798, A190942, A068231.

%K hard,nonn

%O 1,3

%A _Rick L. Shepherd_, Jul 03 2008

%E a(8)-a(10) from _Arkadiusz Wesolowski_, Nov 06 2012