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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 8 |
| 5 | 44 |
| 6 | 333 |
| 7 | 3771 |
| 8 | 67099 |
| 9 | 2026711 |
| 10 | 108874798 |
| 11 | 10682063400 |
[1,1,2,8,44,333,3771,67099,2026711,108874798, 10682063400] |