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Search: id:A052739
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| A052739 |
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A simple context-free grammar in a labeled universe. |
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+0
1
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| 0, 0, 2, 24, 288, 4800, 103680, 2741760, 85800960, 3100446720, 127037030400, 5819550105600, 294727768473600, 16350861400473600, 986127353590579200, 64238655955009536000, 4495021381191204864000, 336249161369543245824000
(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 695
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FORMULA
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E.g.f.: 1/2-1/2*(1-4*x-4*x^2)^(1/2)-x^2-x
Recurrence: {a(1)=0, a(2)=2, a(3)=24, a(4)=288, (-4*n^2+4)*a(n)+(-4*n-2)*a(n+1)+a(n+2)}
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MAPLE
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spec := [S, {B=Prod(Z, Z), S=Prod(C, C), 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: A061190 A002006 A065101 this_sequence A135389 A065513 A119491
Adjacent sequences: A052736 A052737 A052738 this_sequence A052740 A052741 A052742
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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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