A006663 Number of projective meanders.

1, 1, 2, 2, 8, 12, 52, 86, 400, 710, 3404, 6316, 30888, 59204, 293192, 576018, 2877184, 5764430, 28967428, 58970568, 297634344, 614037754, 3109111064

Offset: 0

Author

N. J. A. Sloane, Simon Plouffe

Keywords

• nonn
• nice
• more

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

• 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), no. 1-2, 227-241.

Extensions

a(16)-a(22) from Andrew Howroyd, Mar 30 2017