The first relevant sub-clause is the one labelled '1111111'

Each next relevant sub-clause is the one with a label:
   a) that is one digit longer than that of the previous sub-clause
   b) which contains no previously identified label as a sub-sequence
   c) that is the alphabetically first label complying with a) and b) above.

1     1111111
 2     11111122
 3     111112212
 4     1111122221
 5     11111222222
 6     111122122222
 7     1111222212221
 8     11112222212222
 9     111122222221212
10     1111222222221221
11     111...