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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 24 |
| 5 | 120 |
| 6 | 720 |
| 7 | 4416 |
| 8 | 30744 |
| 9 | 230688 |
| 10 | 2001008 |
| 11 | 18030688 |
| 12 | 182144368 |
| 13 | 1950526752 |
| 14 | 22664810508 |
| 15 | 280110770684 |
| 16 | 3686769376452 |
[1,2,6,24,120,720,4416,30744,230688,2001008, 18030688,182144368,1950526752,22664810508, 280110770684,3686769376452] |