Number of line segments in regular n-gon with all diagonals drawn.

Terms

a(0) =0a(1) =1a(2) =3a(3) =8a(4) =20a(5) =42a(6) =91a(7) =136a(8) =288a(9) =390a(10) =715a(11) =756a(12) =1508a(13) =1722a(14) =2835a(15) =3088a(16) =4896a(17) =4320a(18) =7923a(19) =8360a(20) =12180a(21) =12782a(22) =17963a(23) =16344a(24) =25600a(25) =26494a(26) =35451a(27) =36456a(28) =47908a(29) =38310