Number of 2 X 2 matrices with all terms in {0,1,...,n} and (sum of terms) = n + 5.

Terms

a(0) =0a(1) =0a(2) =4a(3) =31a(4) =80a(5) =146a(6) =224a(7) =315a(8) =420a(9) =540a(10) =676a(11) =829a(12) =1000a(13) =1190a(14) =1400a(15) =1631a(16) =1884a(17) =2160a(18) =2460a(19) =2785a(20) =3136a(21) =3514a(22) =3920a(23) =4355a(24) =4820a(25) =5316a(26) =5844a(27) =6405a(28) =7000a(29) =7630