%I A052652
%S A052652 0,0,0,0,24,240,2880,40320,645120,11612160,232243200,5109350400,
%T A052652 122624409600,3188234649600,89270570188800,2678117105664000,
%U A052652 85699747381248000,2913791410962432000,104896490794647552000
%N A052652 A simple regular expression in a labeled universe.
%H A052652 INRIA Algorithms Project, <a href="http://algo.inria.fr/bin/encyclopedia?Search=ECSnb&argsearch=599">
               Encyclopedia of Combinatorial Structures 599</a>
%F A052652 E.g.f.: -x^4/(-1+2*x)
%F A052652 Recurrence: {a(1)=0, a(0)=0, a(2)=0, a(3)=0, (-2*n-2)*a(n)+a(n+1), a(4)=24}
%F A052652 1/16*2^n*n!
%p A052652 spec := [S,{S=Prod(Z,Z,Z,Z,Sequence(Union(Z,Z)))},labeled]: seq(combstruct[count](spec,
               size=n), n=0..20);
%Y A052652 Sequence in context: A052724 A000536 A151720 this_sequence A052732 A086603 
               A000594
%Y A052652 Adjacent sequences: A052649 A052650 A052651 this_sequence A052653 A052654 
               A052655
%K A052652 easy,nonn
%O A052652 0,5
%A A052652 encyclopedia(AT)pommard.inria.fr, Jan 25 2000