The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 11 |
| 3 | 121 |
| 4 | 1221 |
| 5 | 12321 |
| 6 | 123321 |
| 7 | 1234321 |
| 8 | 12344321 |
| 9 | 123454321 |
| 10 | 1234554321 |
| 11 | 12345654321 |
| 12 | 123456654321 |
| 13 | 1234567654321 |
| 14 | 12345677654321 |
| 15 | 123456787654321 |
| 16 | 1234567887654321 |
| 17 | 12345678987654321 |
[1,11,121,1221,12321,123321,1234321,12344321, 123454321,1234554321,12345654321,123456654321, 1234567654321,12345677654321,123456787654321, 1234567887654321,12345678987654321] |