%I #5 Mar 30 2012 16:50:30
%S 1,3,13,121,4959,2771103,151947502947
%N A102897(n) - 1.
%C Same as A102897, but counts nonempty set systems.
%K nonn
%O 0,2
%A _N. J. A. Sloane_, Mar 17 2007
