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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | -6 |
| 2 | 30 |
| 3 | -156 |
| 4 | 804 |
| 5 | -4152 |
| 6 | 21432 |
| 7 | -110640 |
| 8 | 571152 |
| 9 | -2948448 |
| 10 | 15220704 |
| 11 | -78573504 |
| 12 | 405618240 |
| 13 | -2093913984 |
| 14 | 10809365376 |
| 15 | -55800945408 |
| 16 | 288059973888 |
| 17 | -1487045568000 |
| 18 | 7676542115328 |
| 19 | -39628441869312 |
| 20 | 204573020169216 |
| 21 | -1056062731892736 |
| 22 | 5451689048586240 |
[1,-6,30,-156,804,-4152,21432,-110640,571152, -2948448,15220704,-78573504,405618240,-2093913984, 10809365376,-55800945408,288059973888, -1487045568000,7676542115328,-39628441869312, 204573020169216,-1056062731892736, 5451689048586240] |