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A052737
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a(n)=((2*n)!/n!)*2^(2*n+1).
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0
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0, 2, 16, 384, 15360, 860160, 61931520, 5449973760, 566797271040, 68015672524800, 9250131463372800, 1406019982432665600, 236211357048687820800, 43462889696958559027200
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| A simple context-free grammar in a labeled universe.
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LINKS
| INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 693
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FORMULA
| E.g.f.: 1/4-1/4*(1-16*x)^(1/2)
Recurrence: {a(1)=2, (8-16*n)*a(n)+a(n+1)}
(1/8)*16^(n+1)*GAMMA(n+1/2)/Pi^(1/2)
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MAPLE
| spec := [S, {B=Union(Z, C), S=Union(B, Z, C), C=Prod(S, S)}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
[seq((2*n)!/n!*2^(2*n+1), n=0..12)]; - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Sep 28 2006
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CROSSREFS
| Sequence in context: A015201 A068471 A140308 * A002474 A172149 A012390
Adjacent sequences: A052734 A052735 A052736 * A052738 A052739 A052740
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KEYWORD
| easy,nonn
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AUTHOR
| encyclopedia(AT)pommard.inria.fr, Jan 25 2000
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EXTENSIONS
| Better definition from Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Sep 28 2006
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