%I A052756
%S A052756 0,1,6,81,1728,50625,1889568,85766121,4586471424,282429536481,
%T A052756 19683000000000,1531578985264449,131621703842267136,
%U A052756 12381557655576425121,1265437718438866624512,139628860198736572265625
%N A052756 A simple grammar.
%H A052756 INRIA Algorithms Project, <a href="http://algo.inria.fr/bin/encyclopedia?Search=ECSnb&argsearch=712">
               Encyclopedia of Combinatorial Structures 712</a>
%F A052756 E.g.f.: -1/3*LambertW(-3*x)
%p A052756 spec := [S,{S=Prod(B,B,B,Z),B=Set(S)},labeled]: seq(combstruct[count](spec,
               size=n), n=0..20);
%Y A052756 Sequence in context: A002676 A052348 A064341 this_sequence A138457 A076282 
               A121790
%Y A052756 Adjacent sequences: A052753 A052754 A052755 this_sequence A052757 A052758 
               A052759
%K A052756 easy,nonn
%O A052756 0,3
%A A052756 encyclopedia(AT)pommard.inria.fr, Jan 25 2000