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Search: id:A052734
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| A052734 |
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A simple context-free grammar in a labeled universe. |
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2
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| 0, 1, 8, 192, 7680, 430080, 30965760, 2724986880, 283398635520, 34007836262400, 4625065731686400, 703009991216332800, 118105678524343910400, 21731444848479279513600
(list; graph; listen)
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OFFSET
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0,3
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LINKS
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INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 690
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FORMULA
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E.g.f.: 1/8-1/8*(1-16*x)^(1/2)
Recurrence: {a(1)=1, (8-16*n)*a(n)+a(n+1)}
16^n*GAMMA(n+1/2)/Pi^(1/2)
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MAPLE
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spec := [S, {B=Prod(C, C), S=Union(B, Z), C=Union(B, S, Z)}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
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CROSSREFS
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Sequence in context: A158654 A129004 A058873 this_sequence A003435 A071303 A128406
Adjacent sequences: A052731 A052732 A052733 this_sequence A052735 A052736 A052737
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KEYWORD
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easy,nonn
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AUTHOR
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encyclopedia(AT)pommard.inria.fr, Jan 25 2000
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