Recursion Diagram for Hanoi1 Example with 3 Disks 

Let hnABC be an abbreviation for hanoi(n, "A", "B", "C").
The output always comes between the first (left) recursive 
and second (right) recursive calls.

                      Recursion Tree 
                         h3ABC
               _________/     \_________
              |          AtoB           |
            h2ACB                     h2CBA
        ___/AtoC \___             ___/CtoB \___
       |             |           |             |
     h1ABC        h1BCA        h1CAB         h1ABC
    /AtoB \      /BtoC \      /CtoA \       /AtoB \ 
h0ACB   h0CBA h0BAC  h0ACB h0CBA  h0BAC  h0ACB  h0CBA

Sequence of Activatations, Terminations and Outputs

h3ABC Activated
h2ACB Activated
h1ABC Activated
h0ACB Activated
h0ACB Terminated 
Output A to B
h0CBA Activated
h0CBA Terminated 
h1ABC Terminated
Output A to C
h1BCA Activated
h0BAC Activated
h0BAC Terminated
Output B to C
h0ACB Activated
h0ACB Terminated
h1BCA Terminated
h2ACB Terminated
Output A to B
h2CBA Activated
h1CAB Activated
h0CBA Activated
h0CBA Terminated
Output C to A
h0CBA Activated
h0CBA Terminated
h1CAB Terminated
Output C to B
h1ABC Activated
h0ACB Activated
h0ACB Terminated
Output A to B
h0CBA Activated
h0CBA Terminated
h1ABC Terminated
h2CBA Terminated
h3ABC Terminated