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

0,3

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.

Sequence in context: A001275 A058757 A278455 * A148689 A148690 A148691

Adjacent sequences: A060086 A060087 A060088 * A060090 A060091 A060092

Keyword

nonn

Author

N. J. A. Sloane, Apr 10 2001

Extensions

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

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

Status

approved