Puzzle: numbers

What’s the next line in the following series of numbers?

• 0. length: 11

• 1. length: 211

• 2. length: 221

• 3. length: 41211

• 4. length: 6111221

• 5. length: 6312211

• 6. length: 813112221

• 7. length: 101113213211

• 8. length: 1431131211131221

• 9. length: 2013211311123113112211

• 20. length: 408…

• 30. length: 5808…

• 40. length: 82350…