Motzkin numbers: number of ways of drawing any number of nonintersecting chords joining n (labeled) points on a circle.

A001006

Motzkin numbers: number of ways of drawing any number of nonintersecting chords joining n (labeled) points on a circle.

Terms

    a(0) =1a(1) =1a(2) =2a(3) =4a(4) =9a(5) =21a(6) =51a(7) =127a(8) =323a(9) =835a(10) =2188a(11) =5798a(12) =15511a(13) =41835a(14) =113634a(15) =310572a(16) =853467a(17) =2356779a(18) =6536382a(19) =18199284a(20) =50852019a(21) =142547559a(22) =400763223a(23) =1129760415a(24) =3192727797a(25) =9043402501a(26) =25669818476a(27) =73007772802a(28) =208023278209a(29) =593742784829

External references