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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | -1 |
| 3 | 1 |
| 4 | -2 |
| 5 | 4 |
| 6 | -12 |
| 7 | 36 |
| 8 | -144 |
| 9 | 576 |
| 10 | -2880 |
| 11 | 14400 |
| 12 | -86400 |
| 13 | 518400 |
| 14 | -3628800 |
| 15 | 25401600 |
| 16 | -203212800 |
| 17 | 1625702400 |
| 18 | -14631321600 |
| 19 | 131681894400 |
| 20 | -1316818944000 |
| 21 | 13168189440000 |
| 22 | -144850083840000 |
| 23 | 1593350922240000 |
| 24 | -19120211066880000 |
[0,1,-1,1,-2,4,-12,36,-144,576,-2880,14400,-86400, 518400,-3628800,25401600,-203212800,1625702400, -14631321600,131681894400,-1316818944000, 13168189440000,-144850083840000,1593350922240000, -19120211066880000] |