How can I use a set here to avoid duplication?

Question

This code intends to print sums and lists of coprime numbers modulo. I would like to print the modulo numbers without repetition and have tried to use a set but have encountered problems. Here's the original code. How can I alter this to avoid the repetition.

import math

def IsRelPrime(n):
    arr=[]
    for j in range(1,n+1):
        if math.gcd(n,j)==1:
            arr += [j]
    return(arr)

def Sums(n,mod):
    s=sum(IsRelPrime(n))
    l=len(IsRelPrime(n))
    num_range=list(range(1,n+1))
    res=[i % mod for i in IsRelPrime(n)]
    print ( "The sum of the first %d integers is %d" %(n,sum(num_range)))
    print("The sum of the %d coprime integers is %d:" % (l,s))
    print("The sum of the list modulo %d is %d " % (mod,sum(res)))
    print("The list of integers modulo %d is " % (mod))
    print(*res ,sep = ", ")
    print("The terms relatively prime to %d and %d are %a"  % (n,mod,IsRelPrime(n)))

Sums(15,4)

Here's the output

The sum of the first 15 integers is 120
The sum of the 8 coprime integers is 60:
The sum of the list modulo 4 is 12 
The list of integers modulo 4 is 
1, 2, 0, 3, 0, 3, 1, 2
The terms relatively prime to 15 and 4 are [1, 2, 4, 7, 8, 11, 13, 14]

Answer 1

You can use it in any of the two ways listed below

First

res={i % mod for i in IsRelPrime(n)}

Second

print(*set(res) ,sep = ", ")

Please let me know if comments if you have further questions