Number of ways of arranging n chords on a circle (handshakes between 2n people across a table) with exactly 3 simple intersections.

A232224

Number of ways of arranging n chords on a circle (handshakes between 2n people across a table) with exactly 3 simple intersections.

Terms

    a(0) =0a(1) =0a(2) =0a(3) =1a(4) =20a(5) =195a(6) =1430a(7) =9009a(8) =51688a(9) =278460a(10) =1434120a(11) =7141530a(12) =34648856a(13) =164663785a(14) =769491450a(15) =3546222225a(16) =16152872400a(17) =72846725160a(18) =325722299760

External references