<image> Figures (1), (2), (3), and (4) respectively contain 1, 5, 13, and 25 mascots of the 29th Beijing Olympics "Fuwa Yingying". Construct the figures in the same way. Let the nth figure contain f(n) "Fuwa Yingying". Then f(5) = ____; f(n) - f(n-1) = ____.