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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 2 |
| 3 | -6 |
| 4 | 12 |
| 5 | 200 |
| 6 | -6240 |
| 7 | 139440 |
| 8 | -2869440 |
| 9 | 53386560 |
| 10 | -708048000 |
| 11 | -6667689600 |
| 12 | 1162101600000 |
| 13 | -68789252563200 |
| 14 | 3158414682259200 |
| 15 | -118988867559744000 |
| 16 | 3123174474201600000 |
| 17 | 17680394964750336000 |
| 18 | -10490102782572441600000 |
[0,0,2,-6,12,200,-6240,139440,-2869440,53386560, -708048000,-6667689600,1162101600000, -68789252563200,3158414682259200, -118988867559744000,3123174474201600000, 17680394964750336000,-10490102782572441600000] |