input: Write a python function to calculate the maximum possible sum by recursively dividing a number into three parts and adding them together.
  assert maxDivSum(12) == 13
  assert maxDivSum(24) == 27
  assert maxDivSum(23) == 23
output: def maxDivSum(n):
      if n == 0:
          return 0
      return max(n, maxDivSum(n//2) + maxDivSum(n//3) + maxDivSum(n//4))