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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | -1 |
| 3 | 3 |
| 4 | -14 |
| 5 | 87 |
| 6 | -672 |
| 7 | 6202 |
| 8 | -66622 |
| 9 | 817205 |
| 10 | -11278833 |
| 11 | 173092010 |
| 12 | -2925096344 |
| 13 | 53989582136 |
| 14 | -1080876094507 |
| 15 | 23331975207984 |
| 16 | -540247838958615 |
| 17 | 13357882578863941 |
| 18 | -351281262266717583 |
| 19 | 9790602495326179971 |
| 20 | -288289868480192337409 |
| 21 | 8942994568771904297378 |
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