Number of elements X in the matrix ring M_2(Z_n) such that X^2 == 0 mod n.

Terms

a(0) =1a(1) =4a(2) =9a(3) =28a(4) =25a(5) =36a(6) =49a(7) =112a(8) =153a(9) =100a(10) =121a(11) =252a(12) =169a(13) =196a(14) =225a(15) =640a(16) =289a(17) =612a(18) =361a(19) =700a(20) =441a(21) =484a(22) =529a(23) =1008a(24) =1225a(25) =676a(26) =1377a(27) =1372a(28) =841a(29) =900