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

Terms

a(0) =0a(1) =0a(2) =17a(3) =48a(4) =172a(5) =320a(6) =713a(7) =1112a(8) =2016a(9) =2840a(10) =4561a(11) =6056a(12) =8964a(13) =11400a(14) =15977a(15) =19648a(16) =26400a(17) =31744a(18) =41257a(19) =48664a(20) =61620a(21) =71512a(22) =88689a(23) =101680a(24) =123800a(25) =140376a(26) =168449a(27) =189232a(28) =224108a(29) =249840