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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 3 |
| 4 | 12 |
| 5 | 58 |
| 6 | 355 |
| 7 | 2507 |
| 8 | 20123 |
| 9 | 181332 |
| 10 | 1814067 |
| 11 | 19957313 |
| 12 | 239497077 |
[1,2,3,12,58,355,2507,20123,181332,1814067, 19957313,239497077] |