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Search: id:A052599
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| A052599 |
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A simple regular expression in a labeled universe. |
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+0
1
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| 1, 2, 8, 54, 480, 5280, 69840, 1078560, 19031040, 377758080, 8331724800, 202138675200, 5349968870400, 153396430387200, 4736570917478400, 156702542540544000, 5529893367398400000, 207341583834857472000
(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 544
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FORMULA
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E.g.f.: -1/(-1+2*x+x^3)
Recurrence: {a(0)=1, a(1)=2, a(2)=8, (-11*n-6-n^3-6*n^2)*a(n)+(-2*n-6)*a(n+2)+a(n+3)}
Sum(1/59*(16+12*_alpha^2+9*_alpha)*_alpha^(-1-n), _alpha=RootOf(-1+2*_Z+_Z^3))*n!
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MAPLE
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spec := [S, {S=Sequence(Union(Z, Z, Prod(Z, Z, Z)))}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
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CROSSREFS
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Sequence in context: A079503 A052694 A069729 this_sequence A052662 A073564 A005155
Adjacent sequences: A052596 A052597 A052598 this_sequence A052600 A052601 A052602
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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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