%I A090649
%S A090649 0,1,2,4,5,7,12,13,18,49,55,63,193,247,610,929,2173,3479,5494,11158,
%T A090649 16754,30920,47752
%N A090649 Numbers n such that 9^n + 2 is prime.
%C A090649 All terms are the exact halves of the even terms in A051783. - Alexander 
               Adamchuk (alex(AT)kolmogorov.com), Mar 02 2008
%H A090649 Henri & Renaud Lifchitz, <a href="http://www.primenumbers.net/prptop/
               searchform.php?form=5%5En%2B2&action=Search">PRP Records</a>.
%e A090649 9^13 + 2 = 2541865828331 is prime.
%t A090649 Do[ If[ PrimeQ[9^n + 2], Print[n]], {n, 1, 2250}] (from Robert G. Wilson 
               v Feb 06 2004)
%o A090649 (PARI) for(i=0,700,if(isprime(9^i+2),print(i)))
%Y A090649 Cf. A051783 = Numbers n such that 3^n + 2 is prime. Cf. A087885 = Numbers 
               n such that 5^n + 2 is prime.
%Y A090649 Sequence in context: A022439 A050134 A010065 this_sequence A154686 A165196 
               A007062
%Y A090649 Adjacent sequences: A090646 A090647 A090648 this_sequence A090650 A090651 
               A090652
%K A090649 nonn
%O A090649 1,3
%A A090649 Herman H. Rosenfeld (herm3(AT)pacbell.net), Feb 02 2004
%E A090649 More terms from mohammed bouayoun (bouyao(AT)wanadoo.fr), Feb 04 2004
%E A090649 Further terms from Robert G. Wilson v (rgwv(AT)rgwv.com) and Ray Chandler 
               (rayjchandler(AT)sbcglobal.net), Feb 06 2004
%E A090649 a(20) - a(22) found by Henri Lifchitz, a(23) found by Wojciech Florek. 
               - Jason Earls (zevi_35711(AT)yahoo.com), Feb 25 2008