Find the rules: 1, 11, 21, 1211, 3112

Find the rules: 1, 11, 21, 1211, 3112

1 is all numbers
21 = 11 + 1 = 22 + 1 = 31 + 2 + 1 + 1 = 53 + 1 + 1 + 2 = 7. Then, the first two add up to the third, and so on