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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 7 |
| 5 | 47 |
| 6 | 682 |
| 7 | 23132 |
| 8 | 1913821 |
| 9 | 397731998 |
| 10 | 212521309666 |
| 11 | 297464368728296 |
[1,1,2,7,47,682,23132,1913821,397731998, 212521309666,297464368728296] |