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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 9 |
| 3 | 68 |
| 4 | 5197 |
| 5 | 720447 |
| 6 | 337295264 |
| 7 | 529968166606 |
| 8 | 2583340386672393 |
[1,9,68,5197,720447,337295264,529968166606, 2583340386672393] |