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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 12 |
| 3 | 4 |
| 4 | 1 |
| 5 | 15 |
| 6 | 5 |
| 7 | 57 |
| 8 | 578 |
| 9 | 5789 |
| 10 | 578910 |
| 11 | 57891011 |
| 12 | 5789101112 |
| 13 | 578910111213 |
| 14 | 82701444459 |
| 15 | 27567148153 |
| 16 | 2756714815316 |
| 17 | 275671481531617 |
| 18 | 27567148153161718 |
| 19 | 2756714815316171819 |
| 20 | 275671481531617181920 |
[1,12,4,1,15,5,57,578,5789,578910,57891011, 5789101112,578910111213,82701444459,27567148153, 2756714815316,275671481531617,27567148153161718, 2756714815316171819,275671481531617181920] |