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Number of meanders in which first bridge is 3.
(Formerly M0840)
1

%I M0840 #26 Jun 28 2017 15:17:07

%S 1,1,2,3,7,14,36,81,221,538,1530,3926,11510,30694,92114,252939,773259,

%T 2172830,6743122,19304190,60658606,176343390,559952824,1649008456,

%U 5283239596,15730575554,50789908772,152663683494

%N Number of meanders in which first bridge is 3.

%D 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.

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

%H S. K. Lando and A. K. Zvonkin , <a href="/A005316/a005316_1.pdf">Plane and projective meanders</a>, Séries Formelles et Combinatoire Algébrique. Laboratoire Bordelais de Recherche Informatique, Université Bordeaux I, 1991, pp. 287-303. (Annotated scanned copy)

%Y Cf. A259974, A005316.

%K nonn

%O 3,3

%A _Simon Plouffe_

%E a(19)-a(30) from _Andrew Howroyd_, Dec 15 2015