Number of triangles in an n X n grid (or geoplane).

Terms

a(0) =0a(1) =4a(2) =76a(3) =516a(4) =2148a(5) =6768a(6) =17600a(7) =40120a(8) =82608a(9) =157252a(10) =280988a(11) =477012a(12) =775172a(13) =1214768a(14) =1844512a(15) =2725000a(16) =3930384a(17) =5550844a(18) =7692300a(19) =10482124a(20) =14066996a(21) =18619128a(22) =24337056a(23) =31449200a(24) =40212160a(25) =50921316a(26) =63907468a(27) =79542108