Number of intersections of diagonals in the interior and exterior of a regular n-gon.

Terms

a(0) =0a(1) =1a(2) =5a(3) =13a(4) =42a(5) =73a(6) =189a(7) =271a(8) =572a(9) =661a(10) =1365a(11) =1569a(12) =2790a(13) =3057a(14) =5117a(15) =4555a(16) =8664a(17) =9041a(18) =13797a(19) =14213a(20) =20930a(21) =18625a(22) =30525a(23) =30967a(24) =43092a(25) =43513a(26) =59189a(27) =45871a(28) =79422a(29) =79713