new_contents: """
  
  Calculates the nth number in Sylvester's sequence
  
  Source:
      https://en.wikipedia.org/wiki/Sylvester%27s_sequence
  
  """
  
  
  def sylvester(number: int) -> int:
      """
      :param number: nth number to calculate in the sequence
      :return: the nth number in Sylvester's sequence
  
      >>> sylvester(8)
      113423713055421844361000443
  
      >>> sylvester(-1)
      Traceback (most recent call last):
      ...
      ValueError: The input value of [n=-1] has to be > 0
  
      >>> sylvester(8.0)
      Traceback (most recent call last):
      ...
      AssertionError: The input value of [n=8.0] is not an integer
      """
      assert isinstance(number, int), f"The input value of [n={number}] is not an integer"
  
      if number == 1:
          return 2
      elif number < 1:
          raise ValueError(f"The input value of [n={number}] has to be > 0")
      else:
          num = sylvester(number - 1)
          lower = num - 1
          upper = num
          return lower * upper + 1
  
  
  if __name__ == "__main__":
      print(f"The 8th number in Sylvester's sequence: {sylvester(8)}")
  
subject: Add Sylvester's sequence to maths (#5171)