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A006660 Number of meanders in which first bridge is 3.
(Formerly M0840)
1
1, 1, 2, 3, 7, 14, 36, 81, 221, 538, 1530, 3926, 11510, 30694, 92114, 252939, 773259, 2172830, 6743122, 19304190, 60658606, 176343390, 559952824, 1649008456, 5283239596, 15730575554, 50789908772, 152663683494 (list; graph; refs; listen; history; text; internal format)
OFFSET

3,3

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..30.

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.

Sequence in context: A036250 A191491 A210345 * A306844 A213906 A123777

Adjacent sequences:  A006657 A006658 A006659 * A006661 A006662 A006663

KEYWORD

nonn

AUTHOR

Simon Plouffe

EXTENSIONS

a(19)-a(30) from Andrew Howroyd, Dec 15 2015

STATUS

approved

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Last modified February 16 16:00 EST 2020. Contains 331961 sequences. (Running on oeis4.)