The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 12 |
| 4 | 121 |
| 5 | 21 |
| 6 | 212 |
| 7 | 1212 |
| 8 | 12121 |
| 9 | 2121 |
| 10 | 21212 |
| 11 | 121212 |
| 12 | 1212121 |
| 13 | 212121 |
| 14 | 2121212 |
| 15 | 12121212 |
| 16 | 121212121 |
| 17 | 21212121 |
| 18 | 212121212 |
| 19 | 1212121212 |
| 20 | 12121212121 |
| 21 | 2121212121 |
| 22 | 21212121212 |
| 23 | 121212121212 |
| 24 | 1212121212121 |
| 25 | 212121212121 |
[1,2,12,121,21,212,1212,12121,2121,21212,121212, 1212121,212121,2121212,12121212,121212121, 21212121,212121212,1212121212,12121212121, 2121212121,21212121212,121212121212,1212121212121, 212121212121] |