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Search: id:A052629
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| A052629 |
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A simple regular expression in a labeled universe. |
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+0
1
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| 1, 4, 34, 438, 7536, 162120, 4185360, 126060480, 4339278720, 168038478720, 7230318681600, 342214829510400, 17669683572710400, 988372892015308800, 59538455210371737600, 3842709218808235776000, 264549049753191211008000
(list; graph; listen)
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OFFSET
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0,2
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LINKS
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INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 575
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FORMULA
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E.g.f.: -(-1+x)/(1-5*x+3*x^2)
Recurrence: {a(0)=1, a(1)=4, (3*n^2+9*n+6)*a(n)+(-10-5*n)*a(n+1)+a(n+2)}
Sum(-1/13*(-3+_alpha)*_alpha^(-1-n), _alpha=RootOf(1-5*_Z+3*_Z^2))*n!
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MAPLE
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spec := [S, {S=Sequence(Union(Z, Z, Z, Prod(Z, Sequence(Z))))}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
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CROSSREFS
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Sequence in context: A145349 A052630 A071213 this_sequence A151919 A156325 A111169
Adjacent sequences: A052626 A052627 A052628 this_sequence A052630 A052631 A052632
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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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