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Numbers n such that 11^n + 2 is prime.
12

%I #19 Aug 02 2023 11:46:24

%S 0,1,5,9,287,8273,121185,303909

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

%C No further terms < 100000. - _Ray Chandler_, Jul 30 2011

%C a(8) > 2*10^5. - _Robert Price_, May 11 2014

%e 11^5 + 2 = 161053 is prime, hence 5 is a term.

%t Do[If[PrimeQ[11^n + 2], Print[n]], {n, 0, 5000}]

%o (PARI) is(n)=isprime(11^n+2) \\ _Charles R Greathouse IV_, Feb 17 2017

%K more,nonn

%O 1,3

%A _Ryan Propper_, Jun 17 2005

%E 8273 from _Jason Earls_, Feb 29 2008

%E Edited by _N. J. A. Sloane_, Mar 02 2008

%E a(7) from _Robert Price_, May 11 2014

%E a(8) from _Paul Bourdelais_, Aug 02 2023