Number of 2 X 2 matrices having all terms in {-n,...,0,..,n} and positive odd determinant.

Terms

a(0) =20a(1) =84a(2) =528a(3) =1040a(4) =3060a(5) =4788a(6) =10304a(7) =14400a(8) =26100a(9) =34100a(10) =55440a(11) =69264a(12) =104468a(13) =126420a(14) =180480a(15) =213248a(16) =291924a(17) =338580a(18) =448400a(19) =512400a(20) =660660a(21) =745844a(22) =940608a(23) =1051200a(24) =1301300a(25) =1441908a(26) =1756944a(27) =1932560a(28) =2322900a(29) =2538900