A060111 Dimensions of graded algebra associated with meanders.

1, 4, 15, 56, 207, 764, 2805, 10288, 37609, 137380, 500655, 1823440, 6629423, 24090332, 87418221, 317085352, 1148825185, 4160744164, 15054719697, 54454345624, 196805925995, 711077858188, 2567375653681, 9267176552040, 33430012251123, 120565130387572, 434578910451203

Offset

0,2

Comments

Number of meander slices with n crossings which can be open on both sides and contain no closed loops. These are called 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..27 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. [The final term for a(28) is incorrect].

Crossrefs

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

Sequence in context: A009940 A081163 A082133 * A077824 A291030 A217779

Adjacent sequences: A060108 A060109 A060110 * A060112 A060113 A060114

Keyword

nonn

Author

N. J. A. Sloane, Apr 10 2001

Extensions

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

Status

approved