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A052717
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A simple context-free grammar in a labeled universe.
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0
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0, 0, 2, 6, 48, 600, 10080, 211680, 5322240, 155675520, 5189184000, 194075481600, 8045310873600, 366061644748800, 18134130709094400, 971471287987200000, 55956746188062720000, 3448334483839365120000
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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LINKS
| INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 673
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FORMULA
| E.g.f.: (1/2-1/2*(1-4*x)^(1/2))*x
Recurrence: {a(1)=0, a(3)=6, a(2)=2, (2*n+6-4*n^2)*a(n)+a(n+1)*n}
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MAPLE
| spec := [S, {C=Union(B, Z), B=Prod(C, C), S=Prod(Z, C)}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
with(combinat):with(combstruct):a[0]:=0:for n from 1 to 30 do a[n]:=sum((count(Permutation(n*2-2), size=n-1)), j=0..n) od: seq(a[n], n=0..22); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), May 03 2007
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PROG
| (Mupad) combinat::catalan(n)*(n+2)! $ n = 0..15; - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Feb 15 2007
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CROSSREFS
| Sequence in context: A052743 A052587 A052735 * A175430 A129464 A003053
Adjacent sequences: A052714 A052715 A052716 * A052718 A052719 A052720
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KEYWORD
| easy,nonn
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AUTHOR
| encyclopedia(AT)pommard.inria.fr, Jan 25 2000
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