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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 5 |
| 4 | 161 |
| 5 | 3200 |
| 6 | 314146 |
| 7 | 34323408 |
| 8 | 16813884210 |
| 9 | 8503001699073 |
| 10 | 19277280866911336 |
[1,1,5,161,3200,314146,34323408,16813884210, 8503001699073,19277280866911336] |