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| n | a(n) |
|---|---|
| 1 | 3 |
| 2 | 21 |
| 3 | 120 |
| 4 | 210 |
| 5 | 300 |
| 6 | 10011 |
| 7 | 20100 |
| 8 | 2001000 |
| 9 | 200010000 |
| 10 | 20000100000 |
| 11 | 2000001000000 |
| 12 | 200000010000000 |
| 13 | 20000000100000000 |
| 14 | 2000000001000000000 |
| 15 | 200000000010000000000 |
| 16 | 20000000000100000000000 |
| 17 | 2000000000001000000000000 |
| 18 | 200000000000010000000000000 |
| 19 | 20000000000000100000000000000 |
[3,21,120,210,300,10011,20100,2001000,200010000, 20000100000,2000001000000,200000010000000, 20000000100000000,2000000001000000000, 200000000010000000000,20000000000100000000000, 2000000000001000000000000, 200000000000010000000000000, 20000000000000100000000000000] |