1 -> 1 time 1 = 11
11 -> 2 times 1 = 21
21 -> 1 time 2, 1 time 1 = 1211
1211 -> 1 time 1, 1 time 2, 2 times 1 = 111221
111221 -> 3 times 1, 2 times 2, 1 time 1 = 312211