Number of 2 X 2 matrices with all elements in {0,1,...,n} and determinant in {0,1}.

Terms

a(0) =1a(1) =13a(2) =38a(3) =79a(4) =136a(5) =209a(6) =302a(7) =407a(8) =536a(9) =681a(10) =846a(11) =1015a(12) =1240a(13) =1441a(14) =1678a(15) =1951a(16) =2240a(17) =2505a(18) =2854a(19) =3151a(20) =3552a(21) =3945a(22) =4326a(23) =4687a(24) =5216a(25) =5657a(26) =6110a(27) =6615a(28) =7192a(29) =7649