Number of singular 2 X 2 matrices over Z(n) (i.e., with determinant = 0).

Terms

a(0) =1a(1) =10a(2) =33a(3) =88a(4) =145a(5) =330a(6) =385a(7) =736a(8) =945a(9) =1450a(10) =1441a(11) =2904a(12) =2353a(13) =3850a(14) =4785a(15) =6016a(16) =5185a(17) =9450a(18) =7201a(19) =12760a(20) =12705a(21) =14410a(22) =12673a(23) =24288a(24) =18625a(25) =23530a(26) =26001a(27) =33880a(28) =25201a(29) =47850