Goldbach Conjecture in Python

"""
   Numerical solution to Goldbach’s conjecture.

   Author: Helton Carlos de Souza <heltoncarlossouza@hotmail.com>

   The Goldbach’s Conjecture:
   1) Every even number greater than 2 is the sum of two primes
   2) Every odd number greater than 5 is the sum of three primes.
"""


def divisors(n):
    return [x for x in range(1, n + 1) if n % x == 0]

def is_prime(n):
    return divisors(n) == [1, n]

def prime_range(n):
    return [x for x in range(2, n + 1) if is_prime(x)]

def goldbach_conjecture(n):
    if n % 2 == 0:
        if n > 2:
            return [(x, y) for x in prime_range(n) for y in prime_range(n) if x + y == n and x <= y]
        else:
            raise ValueError('Even numbers must be greater than 2')
    else:
        if n > 5:
            return [(x, y, z) for x in prime_range(n) for y in prime_range(n) for z in prime_range(n) if x + y + z == n and x <= y <= z]
        else:
            raise ValueError('Odd numbers must be greater than 5')

def show_goldbach_conjecture(n):
    tuples_list = goldbach_conjecture(n)
    print(str(n), end='')
    for t in tuples_list:
        print(" = ", end='')
        for index, number in enumerate(t):
            if index == len(t) - 1:
                print(str(number), end='')
            else:
                print(str(number) + " + ", end='')
    print()