Number of 2 X 2 nonsingular 0..n matrices with rows in increasing order.

Terms

a(0) =3a(1) =25a(2) =96a(3) =256a(4) =563a(5) =1073a(6) =1880a(7) =3056a(8) =4715a(9) =6961a(10) =9944a(11) =13752a(12) =18603a(13) =24601a(14) =31936a(15) =40800a(16) =51427a(17) =63937a(18) =78664a(19) =95720a(20) =115435a(21) =138057a(22) =163888a(23) =193064a(24) =226059a(25) =263089a(26) =304480a(27) =350528a(28) =401715a(29) =458145