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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | -1 |
| 3 | 2 |
| 4 | 0 |
| 5 | -6 |
| 6 | 60 |
| 7 | -540 |
| 8 | 3780 |
| 9 | 12600 |
| 10 | -199080 |
| 11 | 3074400 |
| 12 | -45738000 |
| 13 | 511434000 |
| 14 | -5621616000 |
| 15 | 55394539200 |
| 16 | 960323364000 |
| 17 | -24001273296000 |
| 18 | 498178528848000 |
| 19 | -9994137465312000 |
| 20 | 156104172544320000 |
| 21 | -2076607873660320000 |
| 22 | 18061446353670720000 |
| 23 | 206725394268993600000 |
[1,-1,2,0,-6,60,-540,3780,12600,-199080,3074400, -45738000,511434000,-5621616000,55394539200, 960323364000,-24001273296000,498178528848000, -9994137465312000,156104172544320000, -2076607873660320000,18061446353670720000, 206725394268993600000] |