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

Terms

a(0) =0a(1) =3a(2) =20a(3) =48a(4) =144a(5) =243a(6) =528a(7) =768a(8) =1400a(9) =1875a(10) =3060a(11) =3888a(12) =5880a(13) =7203a(14) =10304a(15) =12288a(16) =16848a(17) =19683a(18) =26100a(19) =30000a(20) =38720a(21) =43923a(22) =55440a(23) =62208a(24) =77064a(25) =85683a(26) =104468a(27) =115248a(28) =138600a(29) =151875