%I #15 Mar 31 2012 14:12:21
%S 2,2929,41459,2352527,144937,1055,1829903,7316185805,114491,
%T 3146746271,5028467,20299,69609309001,129433,15307006153,2149705,
%U 66469,559182815,18429503,4529951,7094711,83591212702535,1251548749,38088889
%N a(n) = least k such that 3^k mod k = 2^n.
%F a(n) = A078457(2^n).
%e a(1) = A128149(3) = 2929.
%e a(2) = A128150(3) = 41459.
%Y Cf. A078457 = least k such that the remainder when 3^k is divided by k is n.
%Y Cf. A036236, A128149, A128150.
%K hard,nonn
%O 0,1
%A _Alexander Adamchuk_, Feb 16 2007
%E a(7)-a(9) from A078457. _Max Alekseyev_, Mar 11 2009
%E Extended by _Max Alekseyev_, Mar 15 2009
%E a(20) from _Hagen von Eitzen_, Aug 01 2009
%E a(21)-a(23) from _Max Alekseyev_, Feb 13 2012