Number of segments (and sides) created by diagonals of an n-gon in general position.

Terms

a(0) =3a(1) =8a(2) =20a(3) =45a(4) =91a(5) =168a(6) =288a(7) =465a(8) =715a(9) =1056a(10) =1508a(11) =2093a(12) =2835a(13) =3760a(14) =4896a(15) =6273a(16) =7923a(17) =9880a(18) =12180a(19) =14861a(20) =17963a(21) =21528a(22) =25600a(23) =30225a(24) =35451a(25) =41328a(26) =47908a(27) =55245a(28) =63395a(29) =72416