%I
%S 1,2,3,11,45,51,260,324,390,393,1112,3092,4445,10373,15861,18528,
%T 97715,112961
%N Numbers n such that 9^n  2 is a prime.
%C a(19) > 2*10^5.  _Robert Price_, Aug 18 2014
%t Do[ f = 9^n  2; If[ PrimeQ[ f ], Print[ {n, f} ] ], {n,1,1000} ]
%Y Cf. A084714 = smallest prime of the form (2n1)^k  2, or 0 if no such number exists. Cf. A128472 = smallest prime of the form (2n1)^k  2 for k>(2n1), or 0 if no such number exists. Cf. A014224, A109080, A090669, A128457, A128458, A128459, A128460, A128461.
%K hard,more,nonn
%O 1,2
%A _Alexander Adamchuk_, Mar 14 2007
%E 1112 from _Stefan Steinerberger_, May 05 2007
%E More terms from _Ryan Propper_, Jan 12 2008
%E a(15)a(18) from _Robert Price_, Aug 18 2014
