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Search: id:A008828
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| A008828 |
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Triangle read by rows: T(n,k) = number of closed meander systems of order n with k<=n components. |
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8
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| 1, 2, 2, 8, 12, 5, 42, 84, 56, 14, 262, 640, 580, 240, 42, 1828, 5236, 5894, 3344, 990, 132, 13820, 45164, 60312, 42840, 17472, 4004, 429, 110954, 406012, 624240, 529104, 271240, 85904, 16016, 1430, 933458, 3772008, 6540510, 6413784, 3935238, 1569984
(list; table; graph; listen)
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OFFSET
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1,2
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COMMENT
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A meander of order n has 2n bridges. For many more references, see A005315 and A005316.
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REFERENCES
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S. K. Lando and A. K. Zvonkin "Plane and projective meanders", Theoretical Computer Science Vol. 117 (1993) p232.
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LINKS
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P. Di Francesco, O. Golinelli and E. Guitter, Meander, folding and arch statistics.
I. Jensen, Enumeration of plane meanders
M. La Croix, Approaches to the Enumerative Theory of Meanders [From Gerald McGarvey (gerald.mcgarvey(AT)comcast.net), Oct 26 2008]
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EXAMPLE
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1; 2 2; 8 12 5; 42 84 56 14;...
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CROSSREFS
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Columns include A005315, A006657, A006658. Diagonals include A000108 (Catalan numbers), A006659, A007746. Row sums are in A001246.
Adjacent sequences: A008825 A008826 A008827 this_sequence A008829 A008830 A008831
Sequence in context: A046982 A015620 A046690 this_sequence A053414 A014236 A087955
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KEYWORD
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nonn,tabl,nice
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AUTHOR
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D. Ivanov, S. K. Lando, A. K. Zvonkin ( LabRI, Bordeaux, France).
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EXTENSIONS
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More terms from Pab Ter (pabrlos(AT)yahoo.com), May 10 2004
Edited by Ralf Stephan, Dec 29 2004
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