Number of pairs of 2 X 2 matrices over Z/nZ that commute.

Terms

a(0) =1a(1) =88a(2) =945a(3) =6400a(4) =18625a(5) =83160a(6) =134113a(7) =434176a(8) =741393a(9) =1639000a(10) =1931281a(11) =6048000a(12) =5195905a(13) =11801944a(14) =17600625a(15) =28573696a(16) =25552513a(17) =65242584a(18) =49515121a(19) =119200000a(20) =126736785a(21) =169952728a(22) =154460065a(23) =410296320a(24) =300390625