Number of triangles in an n X n grid of squares with diagonals.

Terms

a(0) =0a(1) =8a(2) =44a(3) =124a(4) =268a(5) =492a(6) =816a(7) =1256a(8) =1832a(9) =2560a(10) =3460a(11) =4548a(12) =5844a(13) =7364a(14) =9128a(15) =11152a(16) =13456a(17) =16056a(18) =18972a(19) =22220a(20) =25820a(21) =29788a(22) =34144a(23) =38904a(24) =44088a(25) =49712a(26) =55796a(27) =62356a(28) =69412a(29) =76980