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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 6 |
| 3 | -12 |
| 4 | -156 |
| 5 | 1680 |
| 6 | 21264 |
| 7 | -592032 |
| 8 | -5349216 |
| 9 | 381679872 |
| 10 | 1095380736 |
| 11 | -384803443200 |
| 12 | 2445989918208 |
| 13 | 547003852781568 |
[0,6,-12,-156,1680,21264,-592032,-5349216, 381679872,1095380736,-384803443200,2445989918208, 547003852781568] |