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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | -1 |
| 3 | 0 |
| 4 | -6 |
| 5 | 8 |
| 6 | -105 |
| 7 | 448 |
| 8 | -3780 |
| 9 | 29360 |
| 10 | -239085 |
| 11 | 2498848 |
| 12 | -23480226 |
| 13 | 280142744 |
| 14 | -3229879653 |
| 15 | 41622253216 |
| 16 | -582786564360 |
| 17 | 8232828649568 |
| 18 | -134282588969529 |
| 19 | 2159014224301504 |
| 20 | -39520792904437310 |
[0,0,-1,0,-6,8,-105,448,-3780,29360,-239085, 2498848,-23480226,280142744,-3229879653, 41622253216,-582786564360,8232828649568, -134282588969529,2159014224301504, -39520792904437310] |