Number of line segments connecting exactly 4 points in an n x n grid of points.

Terms

a(0) =0a(1) =0a(2) =0a(3) =10a(4) =28a(5) =54a(6) =104a(7) =170a(8) =252a(9) =394a(10) =568a(11) =774a(12) =1068a(13) =1410a(14) =1800a(15) =2374a(16) =3028a(17) =3762a(18) =4656a(19) =5646a(20) =6732a(21) =8190a(22) =9792a(23) =11538a(24) =13636a(25) =15910a(26) =18360a(27) =21334a(28) =24532a(29) =27954