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Search: id:A052619
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| A052619 |
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A simple regular expression in a labeled universe. |
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+0
1
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| 0, 0, 0, 18, 72, 360, 2160, 15120, 120960, 1088640, 10886400, 119750400, 1437004800, 18681062400, 261534873600, 3923023104000, 62768369664000, 1067062284288000, 19207121117184000, 364935301226496000
(list; graph; listen)
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OFFSET
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0,4
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LINKS
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INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 564
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FORMULA
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E.g.f.: -3*x^3/(-1+x)
Recurrence: {a(1)=0, a(0)=0, a(2)=0, (-1-n)*a(n)+a(n+1), a(3)=18}
3*n!
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MAPLE
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spec := [S, {S=Prod(Z, Z, Sequence(Z), Union(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: A088490 A069058 A007276 this_sequence A110753 A041626 A039608
Adjacent sequences: A052616 A052617 A052618 this_sequence A052620 A052621 A052622
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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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