4. The following infinite sequence composed of 1s and 2s has an interesting characteristic: starting from the first term, group the terms with the same number together, then write down the number of terms in each group in order, and the infinite sequence formed by these numbers is exactly the sequence itself. This sequence is called the Kolakoski sequence. According to this characteristic, continue to write the next 8 terms of this sequence (from the 13th term to the 20th term),
$1,1,2,1,1,2,2,1$