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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 2 |
| 3 | -6 |
| 4 | 22 |
| 5 | -100 |
| 6 | 668 |
| 7 | -6048 |
| 8 | 64776 |
| 9 | -763488 |
| 10 | 9676152 |
| 11 | -131167080 |
| 12 | 1900043880 |
| 13 | -29387788560 |
| 14 | 484545133200 |
| 15 | -8496674716320 |
| 16 | 158018410132800 |
| 17 | -3107703909004800 |
| 18 | 64445168622156960 |
| 19 | -1405303346393768160 |
[0,0,2,-6,22,-100,668,-6048,64776,-763488,9676152, -131167080,1900043880,-29387788560,484545133200, -8496674716320,158018410132800,-3107703909004800, 64445168622156960,-1405303346393768160] |