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| n | a(n) |
|---|---|
| 2 | 1 |
| 3 | 48 |
| 4 | 284112 |
| 5 | 335750676480 |
| 6 | 112249362914249932800 |
| 7 | 14994936423694913432308324761600 |
[1,48,284112,335750676480,112249362914249932800, 14994936423694913432308324761600] |