$ Aut(U(25)) = Aut(U(5^2)) =Aut(Z_{5^2-5}) =Aut(Z_{20}) =U(20) =U(4) \oplus U(5) =Z_2 \oplus Z_{5-1} =Z_2 \oplus Z_4 $
I think this was the idea. Anyone else do this differently?
