Dihedral unlabeled Motzkin numbers: number of ways of drawing any number of nonintersecting chords joining n unlabeled points equally spaced on a circle, up to rotations and reflections of the circle.
1, 1, 2, 2, 4, 5, 11, 16, 36, 65, 150, 312, 756, 1743, 4353, 10732, 27489, 70379
1 seqfan posts
Tue Feb 8 00:00:06 CET 2011 [seqfan] Re: Unlabeled Motzkin numbers - non-intersecting chords on a free circle