login
A008828
Triangle read by rows: T(n,k) = number of closed meander systems of order n with k<=n components.
11
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, 405552, 63648, 4862
OFFSET
1,2
COMMENTS
A meander of order n has 2n bridges. For many more references, see A005315 and A005316.
LINKS
P. Di Francesco, O. Golinelli and E. Guitter, Meander, folding and arch statistics, arXiv:hep-th/9506030, 1995.
Motohisa Fukuda, Ion Nechita, Enumerating meandric systems with large number of components, arXiv preprint arXiv:1609.02756 [math.CO], 2016.
I. Jensen, Enumeration of plane meanders, arXiv:cond-mat/9910313 [cond-mat.stat-mech], 1999.
S. K. Lando and A. K. Zvonkin, Plane and projective meanders, Séries Formelles et Combinatoire Algébrique. Laboratoire Bordelais de Recherche Informatique, Université Bordeaux I, 1991, pp. 287-303. (Annotated scanned copy)
S. K. Lando and A. K. Zvonkin, Plane and projective meanders, Theoretical Computer Science Vol. 117 (1993) p. 232.
EXAMPLE
Triangle starts:
1;
2 2;
8 12 5;
42 84 56 14;
...
CROSSREFS
Columns include A005315, A006657, A006658. Diagonals include A000108 (Catalan numbers), A006659, A007746. Row sums are in A001246.
Sequence in context: A288053 A288506 A046690 * A254219 A053414 A189837
KEYWORD
nonn,tabl,nice
AUTHOR
D. Ivanov, S. K. Lando, A. K. Zvonkin ( LabRI, Bordeaux, France).
EXTENSIONS
More terms from Pab Ter (pabrlos(AT)yahoo.com), May 10 2004
Edited by Ralf Stephan, Dec 29 2004
T(10,k)-T(20,k) from Andrew Howroyd, Nov 22 2015
STATUS
approved