The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 12 |
| 3 | 123 |
| 4 | 1234 |
| 5 | 12345 |
| 6 | 123456 |
| 7 | 1234567 |
| 8 | 12345678 |
| 9 | 123456789 |
| 10 | 1234567900 |
| 11 | 12345679011 |
| 12 | 123456790122 |
| 13 | 1234567901233 |
| 14 | 12345679012344 |
| 15 | 123456790123455 |
| 16 | 1234567901234566 |
| 17 | 12345679012345677 |
| 18 | 123456790123456788 |
| 19 | 1234567901234567899 |
| 20 | 12345679012345679010 |
[0,1,12,123,1234,12345,123456,1234567,12345678, 123456789,1234567900,12345679011,123456790122, 1234567901233,12345679012344,123456790123455, 1234567901234566,12345679012345677, 123456790123456788,1234567901234567899, 12345679012345679010] |