Automorphisms of The Symmetric and Alternating Groups - Small n - Alternating

Alternating

For n = 1 and 2, A₁ = A₂ = 1 is trivial, so the automorphism group is also trivial. For n = 3, A₃ = C₃ = Z/3 is abelian (and cyclic): the automorphism group is GL(1, Z/3*) = C₂, and the inner automorphism group is trivial (because it is abelian).