Number of 2 X 2 matrices having all terms in {1,...,n} and odd determinant.

Terms

a(0) =0a(1) =6a(2) =40a(3) =96a(4) =288a(5) =486a(6) =1056a(7) =1536a(8) =2800a(9) =3750a(10) =6120a(11) =7776a(12) =11760a(13) =14406a(14) =20608a(15) =24576a(16) =33696a(17) =39366a(18) =52200a(19) =60000a(20) =77440a(21) =87846a(22) =110880a(23) =124416a(24) =154128a(25) =171366a(26) =208936a(27) =230496a(28) =277200a(29) =303750