Number of 2 X 2 matrices with all elements in {0,1,...,n} and determinant >= 3n.

Terms

a(0) =1a(1) =0a(2) =0a(3) =7a(4) =35a(5) =104a(6) =252a(7) =509a(8) =997a(9) =1688a(10) =2751a(11) =4175a(12) =6240a(13) =8872a(14) =12324a(15) =16639a(16) =22196a(17) =28668a(18) =36931a(19) =46332a(20) =58184a(21) =71524a(22) =87183a(23) =105334a(24) =126524a(25) =150233a(26) =177448a(27) =207751a(28) =242948a(29) =281139