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%I #17 Jul 05 2017 02:02:56
%S 0,1,2,5,14,42,138,466,1643,5919,21773,81279,307483,1175352,4534161,
%T 17626999,68992703,271641249,1075144364,4275274867,17071822275,
%U 68428152475,275217386092,1110375948303,4492641333003,18225081419544,74111194585752,302040709982249
%N A simple grammar.
%H Robert Israel, <a href="/A052853/b052853.txt">Table of n, a(n) for n = 0..1000</a>
%H INRIA Algorithms Project, <a href="http://ecs.inria.fr/services/structure?nbr=821">Encyclopedia of Combinatorial Structures 821</a>
%F G.f. appears to be -Sum_{j>=1} (phi(j)/j) * log(1-C(x^j)), where phi = A000010 and C is the g.f. of A050383. - _Robert Israel_, Nov 01 2016
%p spec := [S,{C=Prod(Z,B),S=Cycle(C),B=Set(S)},unlabeled]: seq(combstruct[count](spec,size=n), n=0..20);
%Y Cf. A000010, A050383.
%K easy,nonn
%O 0,3
%A encyclopedia(AT)pommard.inria.fr, Jan 25 2000
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