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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 7 |
| 3 | 39 |
| 4 | 382 |
| 5 | 6840 |
| 6 | 199950 |
| 7 | 10043572 |
| 8 | 854907305 |
| 9 | 123241666053 |
| 10 | 30305450741376 |
[1,7,39,382,6840,199950,10043572,854907305, 123241666053,30305450741376] |