A006658 Closed meanders with 3 components and 2n bridges. (Formerly M4014)

5, 56, 580, 5894, 60312, 624240, 6540510, 69323910, 742518832, 8028001566, 87526544560, 961412790002, 10630964761766, 118257400015312, 1322564193698320, 14863191405246888, 167771227744292160, 1901345329566422790

Offset

3,1

References

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.

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

Table of n, a(n) for n=3..20.

P. Di Francesco, O. Golinelli and E. Guitter, Meander, folding and arch statistics, arXiv:hep-th/9506030, 1995.

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)

Mathematica

A008828 = Import["https://oeis.org/A008828/b008828.txt", "Table"][[All, 2]];
a[n_] := A008828[[(n^2 - n + 6)/2]];
a /@ Range[3, 20] (* Jean-François Alcover, Sep 25 2019 *)

Crossrefs

Cf. A005315, A006657.

A column of triangle A008828.

Sequence in context: A255953 A174249 A073563 * A221160 A006293 A367155

Adjacent sequences: A006655 A006656 A006657 * A006659 A006660 A006661

Keyword

nonn

Author

N. J. A. Sloane

Extensions

a(13)-a(20) from Andrew Howroyd, Nov 22 2015

Status

approved