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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 33 |
| 5 | 351 |
| 6 | 5404 |
| 7 | 104001 |
| 8 | 2416967 |
| 9 | 65820325 |
| 10 | 2058166065 |
| 11 | 72731671225 |
[1,2,5,33,351,5404,104001,2416967,65820325, 2058166065,72731671225] |