Number of 2 X 2 matrices with entries in {0,1,...,n} and even determinant with no entry repeated.

Terms

a(0) =0a(1) =0a(2) =0a(3) =16a(4) =96a(5) =216a(6) =600a(7) =1008a(8) =2064a(9) =3040a(10) =5280a(11) =7200a(12) =11280a(13) =14616a(14) =21336a(15) =26656a(16) =36960a(17) =44928a(18) =59904a(19) =71280a(20) =92160a(21) =107800a(22) =135960a(23) =156816a(24) =193776a(25) =220896a(26) =268320a(27) =302848a(28) =362544a(29) =405720