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

Terms

a(0) =1a(1) =16a(2) =45a(3) =94a(4) =159a(5) =248a(6) =349a(7) =478a(8) =623a(9) =792a(10) =973a(11) =1182a(12) =1423a(13) =1672a(14) =1933a(15) =2238a(16) =2559a(17) =2888a(18) =3261a(19) =3630a(20) =4063a(21) =4504a(22) =4925a(23) =5374a(24) =5935a(25) =6456a(26) =6957a(27) =7534a(28) =8159a(29) =8728