A060089 - OEIS

%I #24 Feb 07 2025 19:38:54

%S 1,1,3,7,23,63,213,627,2149,6597,22787,71883,249523,802291,2794365,

%T 9111917,31814061,104862813,366796437,1219313185,4271041447,

%U 14295561451,50131159253,168742700865,592279599483,2003050663889,7035894016347,23890177457535,83968962295531

%N Dimensions of graded algebra associated with meanders (subalgebra version).

%C Number of meander slices with n crossings which are closed on one side and contain no closed loops. These are called unidirectional open meandric systems in the Bobier and Sawada reference. - _Andrew Howroyd_, Feb 07 2025

%H Andrew Howroyd, <a href="/A060089/b060089.txt">Table of n, a(n) for n = 0..40</a> (terms 0..28 from B. Bobier and J. Sawada)

%H Roland Bacher, <a href="https://www-fourier.ujf-grenoble.fr/?q=en/content/meander-algebras">Meander algebras</a>, Institut Fourier, UMR 5582, Laboratoire de Mathématiques, 1999.

%H B. Bobier and J. Sawada, <a href="http://www.cis.uoguelph.ca/~sawada/papers/meander.pdf">A fast algorithm to generate open meandric systems and meanders</a>, Transactions on Algorithms, Vol. 6 No. 2 (2010) article #42, 12 pages.

%Y Meander sequences in Bacher's paper: A005315, A060066, A060089, A060111, A060148, A060149, A060174, A060198, A060206.

%K nonn

%O 0,3

%A _N. J. A. Sloane_, Apr 10 2001

%E More terms from Larry Reeves (larryr(AT)acm.org), Apr 26 2001

%E Further terms from the Bobier-Sawada paper, Jul 28 2007