Number of ways to choose three points in an (n X n)-grid (or geoplane).

Terms

a(0) =0a(1) =4a(2) =84a(3) =560a(4) =2300a(5) =7140a(6) =18424a(7) =41664a(8) =85320a(9) =161700a(10) =287980a(11) =487344a(12) =790244a(13) =1235780a(14) =1873200a(15) =2763520a(16) =3981264a(17) =5616324a(18) =7775940a(19) =10586800a(20) =14197260a(21) =18779684a(22) =24532904a(23) =31684800a(24) =40495000a(25) =51257700a(26) =64304604a(27) =80007984a(28) =98783860a(29) =121095300