%I A052864
%S A052864 0,0,2,12,82,670,6458,72072,915864,13068768,206998032,3604604256,
%T A052864 68455569840,1408152976464,31191374639280,740216664633984,
%U A052864 18736923967232256,503916672279712896,14349543617967990912
%N A052864 A simple grammar.
%H A052864 INRIA Algorithms Project, <a href="http://algo.inria.fr/bin/encyclopedia?Search=ECSnb&argsearch=832">
               Encyclopedia of Combinatorial Structures 832</a>
%F A052864 E.g.f.: -ln(-1/(-1+x))^2/(-1+ln(-1/(-1+x)))
%p A052864 spec := [S,{C=Cycle(Z),B=Sequence(C,1 <= card),S=Prod(B,C)},labeled]: 
               seq(combstruct[count](spec,size=n), n=0..20);
%Y A052864 Cf. A009122.
%Y A052864 Sequence in context: A058872 A055548 A092850 this_sequence A130464 A006657 
               A105927
%Y A052864 Adjacent sequences: A052861 A052862 A052863 this_sequence A052865 A052866 
               A052867
%K A052864 easy,nonn
%O A052864 0,3
%A A052864 encyclopedia(AT)pommard.inria.fr, Jan 25 2000