Number of obtuse triangles made from vertices of a regular n-gon.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =0a(5) =5a(6) =6a(7) =21a(8) =24a(9) =54a(10) =60a(11) =110a(12) =120a(13) =195a(14) =210a(15) =315a(16) =336a(17) =476a(18) =504a(19) =684a(20) =720a(21) =945a(22) =990a(23) =1265a(24) =1320a(25) =1650a(26) =1716a(27) =2106a(28) =2184a(29) =2639