%I A052850
%S A052850 0,2,5,20,114,864,8280,96480,1325520,20966400,374855040,7468070400,
%T A052850 163938297600,3929729126400,102104460057600,2857878742118400,
%U A052850 85719362496768000,2742726680838144000,93247371837075456000
%N A052850 A simple grammar.
%H A052850 INRIA Algorithms Project, <a href="http://algo.inria.fr/bin/encyclopedia?Search=ECSnb&argsearch=818">
               Encyclopedia of Combinatorial Structures 818</a>
%F A052850 E.g.f.: (-x-ln((-1+x)/(-1+2*x))+ln((-1+x)/(-1+2*x))*x)/(-1+x)
%F A052850 Recurrence: {a(1)=2, a(2)=5, a(3)=20, a(4)=114, (2*n^3-2*n)*a(n)+(-3*n^2+2*n+5)*a(n+1)+(-2+n)*a(n+2)}
%p A052850 spec := [S,{B=Sequence(Z,1 <= card),C=Cycle(B),S=Union(B,C)},labeled]: 
               seq(combstruct[count](spec,size=n), n=0..20);
%Y A052850 Sequence in context: A129949 A127065 A168357 this_sequence A000130 A009599 
               A112833
%Y A052850 Adjacent sequences: A052847 A052848 A052849 this_sequence A052851 A052852 
               A052853
%K A052850 easy,nonn
%O A052850 0,2
%A A052850 encyclopedia(AT)pommard.inria.fr, Jan 25 2000