%I A052505
%S A052505 1,3,300,141120,182952000,505008504000,2547446533632000
%N A052505 Number of labeled 3-constrained functional graphs.
%H A052505 INRIA Algorithms Project, <a href="http://algo.inria.fr/bin/encyclopedia?Search=ECSnb&argsearch=38">
               Encyclopedia of Combinatorial Structures 38</a>
%F A052505 E.g.f.: -2/(-2+x*RootOf(-6*_Z+6*x+x*_Z^3)^2)
%F A052505 Recurrence: {a(1)=0, (-9*n^4-54*n^3-117*n^2-108*n-36)*a(n)+(8*n+12)*a(n+3), 
               a(2)=0, a(4)=0, a(3)=3, a(5)=0}
%p A052505 spec := [S,{g=Union(Z,Prod(Z,Set(g,card=3))),S=Set(Cycle(Prod(Z,Set(g,
               card=2))))},labeled]: seq(combstruct[count](spec,size=n), n=0..20);
%Y A052505 Sequence in context: A119059 A119049 A119067 this_sequence A071525 A157583 
               A085319
%Y A052505 Adjacent sequences: A052502 A052503 A052504 this_sequence A052506 A052507 
               A052508
%K A052505 easy,nonn
%O A052505 0,2
%A A052505 encyclopedia(AT)pommard.inria.fr, Jan 25 2000