A060089 Dimensions of graded algebra associated with meanders (subalgebra version).

1, 1, 3, 7, 23, 63, 213, 627, 2149, 6597, 22787, 71883, 249523, 802291, 2794365, 9111917, 31814061, 104862813, 366796437, 1219313185, 4271041447, 14295561451, 50131159253, 168742700865, 592279599483, 2003050663889, 7035894016347, 23890177457535, 83968962295531

Offset: 0

Author

N. J. A. Sloane, Apr 10 2001

Keywords

• nonn

Comments

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

Links

• Andrew Howroyd, Table of n, a(n) for n = 0..40 (terms 0..28 from B. Bobier and J. Sawada)
• Roland Bacher, Meander algebras, Institut Fourier, UMR 5582, Laboratoire de Mathématiques, 1999.
• B. Bobier and J. Sawada, A fast algorithm to generate open meandric systems and meanders, Transactions on Algorithms, Vol. 6 No. 2 (2010) article #42, 12 pages.

Crossrefs

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

Extensions

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

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