In mathematics, the nth Motzkin number is the number of different ways of drawing non-intersecting chords between n points on a circle. Wikipedia

Number of patterns of non-intersecting chords with a given number of endpoints on a circle Wikidata

For a given number n, the number of different ways of drawing non-intersecting chords between n points on a circle (not necessarily touching every point by a chord). They have diverse applications in geometry, combinatorics, and number theory. Wiktionary