Proof of Bertrand's Theorem

bertrand.py3

# We know for sure based upon "M. El Bachraoui, Bertrand’s postulate for high–school students, International Journal of Mathematical Education, 9 (2019), 73–77" that the postulate is true for n>112.
# Therefore, it is necessary a proof by exhaustion until 113 - this is the porpouse of this Python's algorithm.
def isprime(n):
    for num in range(2,n):
        if (n%num)==0:
            return False
    return True
def validatetheorem(num):
    for i in range(n, 2*n+1):
        if isprime(i):
            return True
for n in range(1,114):
    if validatetheorem(n):
        print(n, "is valid")

Bertrand's Postulate: Given a number, we know for sure that exists a p such that: n<= p <= 2n