input: Write a python function to find numbers with both the 0th and nth bits set.  
  assert find_Num(2) == 1  
  assert find_Num(3) == 2  
  assert find_Num(1) == 1
output: def find_Num(n):
      result = []
      for i in range(1, 1 << (n + 1)):
          if (i & 1) and (i & (1 << n)):
              result.append(i)
      return len(result)