%I #3 Mar 30 2012 16:50:11
%S 2,6,70,1180591620717411303494
%N a(0) = 2; a(n+1) = 2^a(n) + a(n).
%K nonn
%O 0,1
%A _N. J. A. Sloane_, Mar 21 2005
%E The next term is too large to include.
