%I A052629
%S A052629 1,4,34,438,7536,162120,4185360,126060480,4339278720,168038478720,
%T A052629 7230318681600,342214829510400,17669683572710400,988372892015308800,
%U A052629 59538455210371737600,3842709218808235776000,264549049753191211008000
%N A052629 A simple regular expression in a labeled universe.
%H A052629 INRIA Algorithms Project, <a href="http://algo.inria.fr/bin/encyclopedia?Search=ECSnb&argsearch=575">
               Encyclopedia of Combinatorial Structures 575</a>
%F A052629 E.g.f.: -(-1+x)/(1-5*x+3*x^2)
%F A052629 Recurrence: {a(0)=1, a(1)=4, (3*n^2+9*n+6)*a(n)+(-10-5*n)*a(n+1)+a(n+2)}
%F A052629 Sum(-1/13*(-3+_alpha)*_alpha^(-1-n), _alpha=RootOf(1-5*_Z+3*_Z^2))*n!
%p A052629 spec := [S,{S=Sequence(Union(Z,Z,Z,Prod(Z,Sequence(Z))))},labeled]: seq(combstruct[count](spec,
               size=n), n=0..20);
%Y A052629 Sequence in context: A145349 A052630 A071213 this_sequence A151919 A156325 
               A111169
%Y A052629 Adjacent sequences: A052626 A052627 A052628 this_sequence A052630 A052631 
               A052632
%K A052629 easy,nonn
%O A052629 0,2
%A A052629 encyclopedia(AT)pommard.inria.fr, Jan 25 2000