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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | -4 |
| 4 | 28 |
| 5 | -236 |
| 6 | 2159 |
| 7 | -20309 |
| 8 | 189387 |
| 9 | -1696165 |
| 10 | 14092143 |
| 11 | -103605487 |
| 12 | 621674576 |
| 13 | -2503235595 |
| 14 | 1311059747 |
| 15 | 58857366823 |
| 16 | -625935119621 |
| 17 | 20416246154579 |
| 18 | -595556154741631 |
| 19 | 9331660766550500 |
| 20 | -50486760747953952 |
| 21 | -816026626910008666 |
[1,1,-4,28,-236,2159,-20309,189387,-1696165, 14092143,-103605487,621674576,-2503235595, 1311059747,58857366823,-625935119621, 20416246154579,-595556154741631,9331660766550500, -50486760747953952,-816026626910008666] |