Number of 2 X 2 nonsingular matrices having all terms in {-n,...,0,...,n}.

Terms

a(0) =48a(1) =496a(2) =2112a(3) =6016a(4) =13808a(5) =27248a(6) =48896a(7) =81152a(8) =127280a(9) =190576a(10) =275264a(11) =384768a(12) =524784a(13) =699376a(14) =914176a(15) =1175040a(16) =1488688a(17) =1860208a(18) =2298304a(19) =2808320a(20) =3399280a(21) =4079088a(22) =4856704a(23) =5738624a(24) =6736944a(25) =7859824a(26) =9117376a(27) =10519424