input: Write a python function to check if a specified number exists within an infinite sequence.
  assert is_Number_in_Sequence(1,7,3) == True
  assert is_Number_in_Sequence(1,-3,5) == False
  assert is_Number_in_Sequence(3,2,5) == False
output: def is_Number_in_Sequence(a, b, n):
      if b == 0:
          return a == n
      return (n - a) % b == 0 and (n - a) // b >= 0