Solution to: Strange Sequence

Again, the system behind the sequence is that each number (except the first one of the sequence) "describes" the previous number. Now, however, the number of occurrences of each digit is counted. So 1231 means one "2" and three times a "1", and 131221 means one "3", one "2", and two times a "1". The number following on 131221 is therefore 132231 (one "3", two times a "2", and three times a "1"). The complete sequence is as follows:

1 11 21 1211 1231 131221 132231 232221 134211 14131231 14231241 24132231 14233221 14233221 etcetera

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