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| n | a(n) |
|---|---|
| 3 | 1 |
| 4 | 18 |
| 5 | 43920 |
| 6 | 4397760 |
| 7 | 122377651200 |
| 8 | 30993058252800 |
| 9 | 3921055557027840000 |
| 10 | 711860093387348628602880000 |
| 11 | 551343268152723132127641600000 |
| 12 | 567168796017902020698219516788736000000 |
[1,18,43920,4397760,122377651200,30993058252800, 3921055557027840000,711860093387348628602880000, 551343268152723132127641600000, 567168796017902020698219516788736000000] |