%I A068531
%S A068531 1,5,205,672605,14476720225405,13412827423017626893194723005,
%T A068531 23027704253395670256876704807446325518902757016163752166205,
%U A068531 1357504417745554030907615105367786163224793464927042363199265863574571021775062850986345401895601655486442046\
               29442284605
%N A068531 a(n)=(3^(2^n)-1)/2^(n+2).
%C A068531 Every element of this sequence is an odd number (see link). - Graeme 
               McRae (g_m(AT)mcraefamily.com), Jan 12 2005
%H A068531 Graeme McRae, <a href="http://2000clicks.com/MathHelp/PuzzlePowersOf3AndPowersOf2Answer.htm">
               Proof: for every positive integer k, there exists a positive integer 
               m such that 3^m+5 is divisible by 2^k.</a>
%Y A068531 Sequence in context: A002438 A005333 A162087 this_sequence A144139 A020541 
               A027682
%Y A068531 Adjacent sequences: A068528 A068529 A068530 this_sequence A068532 A068533 
               A068534
%K A068531 easy,nonn
%O A068531 1,2
%A A068531 Benoit Cloitre (benoit7848c(AT)orange.fr), Mar 22 2002