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

Terms

a(0) =0a(1) =0a(2) =0a(3) =1a(4) =5a(5) =13a(6) =35a(7) =49a(8) =126a(9) =161a(10) =330a(11) =301a(12) =715a(13) =757a(14) =1365a(15) =1377a(16) =2380a(17) =1837a(18) =3876a(19) =3841a(20) =5985a(21) =5941a(22) =8855a(23) =7297a(24) =12650a(25) =12481a(26) =17550a(27) =17249a(28) =23751a(29) =16801