input: def sum_powered(lst):
      """
      This function receives a list of integers. It will square each integer if its index is a multiple of 3, and cube each integer if its index is a multiple of 4 but not a multiple of 3. The entries at indexes which are neither multiples of 3 nor 4 will remain unchanged. Finally, the function will return the total sum of all entries.
      
      Examples:
      For lst = [1,2,3] the result should be 6
      For lst = [] the result should be 0
      For lst = [-1,-5,2,-1,-5] the result should be -126
      """
output:     result = 0
      for i, num in enumerate(lst):
          if i % 3 == 0:
              result += num ** 2
          elif i % 4 == 0:
              result += num ** 3
          else:
              result += num
      return result