input: Write a python function to generate a series of random numbers.
  assert len(generate_random_series(5)) == 5
  assert len(generate_random_series(10)) == 10
  assert all(0 <= num <= 1000 for num in generate_random_series(15))
output: import random
  
  def generate_random_series(n):
      return [random.randint(0, 1000) for _ in range(n)]