Given an integer n, one can define in SageMath the additive group Z/nZ by
sage: Zn = Zmod(n) # or Integers(n)
Now, I would like to work in the multiplicative group (Z/nZ)∗. Of course, I can write
sage: G = [a for a in Zn if gcd(a,n) == 1]
What I would like is an easier way of writing such a thing, such as:
sage: G = Zn.multiplicative_group() #does not exist!
And then, I could for instance write something like: