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**knguyen2005** 1) What is Aut(G) and how do you show that the automorphism is isomorphic to a group i.e. Aut(C5) =~ C4, and what is Aut(C9) is isomorphic to which cyclic group, is it group C8?

2) Describe Aut(Cn) explicitly for n = 24

How do you show that Aut(C12) =~ C2 * C2 and Aut(C14) =~ C6 ?. Find the correspoding isomorphism for Aut(C24)

Another question is: Does it mean that, C2 * C2 = C4

C4 * C4 = C16

C5 * C5 = C25

and so on ... so in general Cn * Cn = C(n*n). I dont know

Can any body help please? I'd appreciate your help.

Many thanks