Number of acute triangles on an n X n grid (or geoboard).

Terms

a(0) =0a(1) =0a(2) =8a(3) =80a(4) =404a(5) =1392a(6) =3880a(7) =9208a(8) =19536a(9) =38096a(10) =69288a(11) =119224a(12) =196036a(13) =310008a(14) =474336a(15) =705328a(16) =1023216a(17) =1451904a(18) =2020232a(19) =2762848a(20) =3719420a(21) =4937200a(22) =6469424a(23) =8378184a(24) =10734664a(25) =13618168a(26) =17119288a(27) =21338760a(28) =26390452a(29) =32400592