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%I #18 Sep 08 2022 08:45:08
%S 1,2,21,25,33,54,78,235,1566,2273,2310,4121,7775,42249,105974,138961
%N Numbers n such that 11*12^n -1 is prime.
%C a(17) > 2*10^5. - _Robert Price_, Mar 20 2015
%D R. K. Guy, Unsolved Problems in Theory of Numbers, Section A3.
%H Steven Harvey, <a href="http://harvey563.tripod.com/wills.txt">Williams Primes</a>
%H H. C. Williams, <a href="http://matwbn.icm.edu.pl/ksiazki/aa/aa39/aa3912.pdf">The primality of certain integers of the form 2Ar^n - 1</a>, Acta Arith. 39 (1981), 7-17.
%t Do[ If[ PrimeQ[11*12^n - 1], Print[n]], {n, 1, 2000}]
%t Select[Range[10000], PrimeQ[(11 12^# - 1)] &] (* _Vincenzo Librandi_, Mar 21 2015 *)
%o (PARI) for(n=1,2000, if(isprime(11*12^n-1),print1(n, ", ")))
%o (Magma) [n: n in [1..600]| IsPrime(11*12^n - 1)]; // _Vincenzo Librandi_, Mar 21 2015
%Y Cf. A003307, A002235, A046865, A079906, A046866, A001771, A005541, A056725, A046867.
%K nonn,hard
%O 1,2
%A _Robert G. Wilson v_, Jan 16 2003
%E More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 05 2008
%E a(13)-a(16) from _Robert Price_, Mar 20 2015
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