A006661 Number of meanders in which first bridge is 5.

3, 3, 7, 11, 28, 57, 155, 353, 1003, 2458, 7214, 18575, 55880, 149183, 457639, 1255933, 3914103, 10978240, 34663182, 98953078, 315884786, 915008430, 2948378068, 8645874055, 28084475514, 83222134020

Offset: 5

Author

Simon Plouffe

Keywords

• nonn

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)

Crossrefs

Cf. A259974, A005316.

Extensions

Offset corrected terms a(19)-a(30) added, Andrew Howroyd, Dec 15 2015