Prime numbers/Prime number generators

This code is used on Python3.

from tqdm import tqdm

def is_prime(n):
  if n == 2 or n == 3: return True
  if n < 2 or n%2 == 0: return False
  if n < 9: return True
  if n%3 == 0: return False
  r = int(n**0.5)
  f = 5
  while f <= r:
    if n%f == 0: return False
    if n%(f+2) == 0: return False
    f +=6
  return True  
  
def prime_gen(amt):
    n = 1
    cur = 0
    while True:
        if not is_prime(n):
            n += 1
        else:
            yield n
            n += 1
            cur += 1
        if cur == amt:
            break
			
def prime_filegen(pn):
    with open('primes_{}.txt'.format(str(pn)),'w') as file:
        for i in tqdm(prime_gen(pn), total = pn):
            f = file.write('# '+str(i)+'\n')

The purpose of tqdm is to provide a nice progressbar for progress. It can be removed by replacing the second-to-last with

       for i in prime_gen(pn):

and removing the first line.