Number of obtuse triangles, distinct up to congruence, on an n X n grid (or geoboard).

Terms

a(0) =0a(1) =0a(2) =2a(3) =12a(4) =39a(5) =95a(6) =193a(7) =355a(8) =597a(9) =943a(10) =1426a(11) =2071a(12) =2904a(13) =3977a(14) =5306a(15) =6956a(16) =8963a(17) =11370a(18) =14225a(19) =17587a(20) =21515a(21) =26053a(22) =31310a(23) =37282a(24) =44061a(25) =51785a(26) =60436a(27) =70127a(28) =80939a(29) =92952