Homework Statement
Determine all integers for which there exists a unique abelian group of order n.
Homework Equations
The Attempt at a Solution
All prime integers?
Homework Statement
Show that the number of group homomorphisms from Zn to Zm is equal to gcd(n,m).
my attempt:
any hom from Zn to Zm must be f([x])=[kx] where k is a common factor of n and m. I can only get this far... any help is appreciated.