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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 56 |
| 4 | 2520 |
| 5 | 666624 |
| 6 | 839946240 |
| 7 | 3343877406720 |
| 8 | 41781748196966400 |
| 9 | 3701652434038082764800 |
| 10 | 763416952708225267547504640 |
| 11 | 750836199529096452135514747699200 |
[1,3,56,2520,666624,839946240,3343877406720, 41781748196966400,3701652434038082764800, 763416952708225267547504640, 750836199529096452135514747699200] |