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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 2 |
| 3 | -6 |
| 4 | 34 |
| 5 | -220 |
| 6 | 1688 |
| 7 | -14868 |
| 8 | 147684 |
| 9 | -1631376 |
| 10 | 19821912 |
| 11 | -262573080 |
| 12 | 3764276712 |
| 13 | -58044604176 |
| 14 | 957653604672 |
| 15 | -16828739439120 |
| 16 | 313742795670288 |
| 17 | -6183918938706048 |
| 18 | 128463999017594016 |
| 19 | -2804979941504113248 |
[1,0,2,-6,34,-220,1688,-14868,147684,-1631376, 19821912,-262573080,3764276712,-58044604176, 957653604672,-16828739439120,313742795670288, -6183918938706048,128463999017594016, -2804979941504113248] |