This is a modified problem about the Tower of Hanoi, where there is an extra condition while solving the problem:

Consider the Tower of Hanoi problem with peg A, B and C. We want to transfer a tower of n disks from peg A to peg B, if direct moves between A and B are disallowed. (Each move must be to or from peg C. As usual, a larger disk must never appear above a smaller one.) (a) Write a pseudocode to solve the problem recursively. (b) Set up a recurrence equation to count the number of steps to move n disks using your method in (a). (c) Solve the recurrence and give the complexity of your algorithm.