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Search: id:A052654
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| A052654 |
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A simple regular expression in a labeled universe. |
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+0
1
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| 1, 5, 42, 510, 8184, 163800, 3931920, 110098800, 3523201920, 126835632000, 5073428908800, 223230911904000, 10715084250393600, 557184387247488000, 31202325773037619200, 1872139547689931520000, 119816931073078407168000
(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 601
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FORMULA
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E.g.f.: 1/(-1+x)/(-1+4*x)
Recurrence: {a(0)=1, a(1)=5, (4*n^2+12*n+8)*a(n)+(-10-5*n)*a(n+1)+a(n+2)}
(-1/3+1/3*4^(n+1))*n!
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MAPLE
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spec := [S, {S=Prod(Sequence(Z), Sequence(Union(Z, 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: A005789 A151334 A102693 this_sequence A108398 A102244 A132487
Adjacent sequences: A052651 A052652 A052653 this_sequence A052655 A052656 A052657
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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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