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| n | a(n) |
|---|---|
| 3 | -2 |
| 4 | 0 |
| 5 | -2 |
| 6 | 4480 |
| 7 | -2 |
| 8 | 274560 |
| 9 | -1076275202 |
| 10 | 20650240 |
| 11 | -595948953602 |
| 12 | 3337315890251520 |
| 13 | -317541467443202 |
| 14 | 8443404916271478400 |
| 15 | -61468170244569234432002 |
| 16 | 17796778320664208810880 |
| 17 | -497337594356972616069888002 |
| 18 | 4456181603844910120400213608960 |
[-2,0,-2,4480,-2,274560,-1076275202,20650240, -595948953602,3337315890251520,-317541467443202, 8443404916271478400,-61468170244569234432002, 17796778320664208810880, -497337594356972616069888002, 4456181603844910120400213608960] |