<image> As shown in the figure: There are three pegs and several metal disks stacked on one of the pegs. According to the following rules, transfer all the metal disks from one peg to another.
(1) Only one metal disk can be moved at a time;
(2) During each move, a larger metal disk cannot be placed on top of a smaller one on any peg. The minimum number of moves required to transfer n metal disks from peg 1 to peg 3 is denoted as f(n);
① f(3) = ____;
② f(n) = ____.