In combinatorics there are there are special kind of sequences, in which their terms represent the number of different ways that we can draw chords with some properties.
Actually my question is motivated by the following examples of what I have mentioned earlier.
Motzkin number (The number of different ways of drawing non-intersecting chords on a circle between n points)
Bell number (the number of partitions of a set of size n, in this case the drawing of the chords is described in the link)
Catalan number(number of non crossing partitions of some sets)
My question is that, can you, please, tell me similar sequences?