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

Terms

a(0) =4a(1) =80a(2) =428a(3) =1428a(4) =3604a(5) =7924a(6) =14988a(7) =26244a(8) =43072a(9) =66844a(10) =98804a(11) =142652a(12) =197584a(13) =268800a(14) =357608a(15) =465888a(16) =596964a(17) =756036a(18) =942160a(19) =1163608a(20) =1420248a(21) =1717344a(22) =2056952a(23) =2451248a(24) =2891420a(25) =3392528a(26) =3958576