A060174 Dimensions of graded algebra associated with forest meanders (subalgebra version).

1, 4, 32, 320, 3536, 41344, 501264, 6232736, 78948912, 1014329856, 13178920016, 172789849952, 2282474558160, 30340247738176, 405461900524400, 5443463231234592, 73372619284217776, 992459740253399360, 13465895431077568080, 183211658096891394848, 2498857102607629076880

Offset

0,2

Comments

Number of meander slices with 2n crossings which are closed on one side and whose loops are all even. A loop is even if it has its least point at an even index with crossings numbered from zero. - Andrew Howroyd, Feb 07 2025

Links

Table of n, a(n) for n=0..20.

Roland Bacher, Meander algebras, Institut Fourier, UMR 5582, Laboratoire de Mathématiques, 1999.

Crossrefs

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

Sequence in context: A260155 A047734 A220118 * A052704 A151403 A289427

Adjacent sequences: A060171 A060172 A060173 * A060175 A060176 A060177

Keyword

nonn

Author

N. J. A. Sloane, Apr 10 2001

Extensions

Offset corrected and a(7) onwards from Andrew Howroyd, Jan 31 2025

Status

approved