Number of lines through exactly 3 points of an n X n grid of points.

Terms

a(0) =0a(1) =0a(2) =0a(3) =8a(4) =4a(5) =16a(6) =36a(7) =64a(8) =100a(9) =204a(10) =252a(11) =396a(12) =572a(13) =780a(14) =1020a(15) =1484a(16) =1756a(17) =2260a(18) =2828a(19) =3540a(20) =4332a(21) =5556a(22) =6372a(23) =7716a(24) =9188a(25) =10684a(26) =12292a(27) =14684a(28) =16588a(29) =19324