Number of invertible 2 X 2 matrices mod n.

Terms

a(0) =1a(1) =6a(2) =48a(3) =96a(4) =480a(5) =288a(6) =2016a(7) =1536a(8) =3888a(9) =2880a(10) =13200a(11) =4608a(12) =26208a(13) =12096a(14) =23040a(15) =24576a(16) =78336a(17) =23328a(18) =123120a(19) =46080a(20) =96768a(21) =79200a(22) =267168a(23) =73728a(24) =300000a(25) =157248a(26) =314928a(27) =193536a(28) =682080a(29) =138240