[seqfan] unlabeled Motzkin numbers

Max Alekseyev maxale at gmail.com
Wed Oct 27 20:40:50 CEST 2010

Just out of curiosity, what would be an "unlabeled" version of Motzkin
numbers A001006?
That is, number of ways of drawing any number of nonintersecting
chords joining n unlabeled equally spaced points on a circle (in other
words, the points and chords are distinguished up to rotations of the
Is this sequence in the OEIS?

Furthermore, is there a variant of counting up to rotations and
reflections of the circle?


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