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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 10 |
| 4 | 280 |
| 5 | 60060 |
| 6 | 85765680 |
| 7 | 2061378118800 |
| 8 | 346915095471584640 |
| 9 | 1736278161426147413954880 |
| 10 | 62144711688730139887005809020800 |
| 11 | 103104526145243794108489566205445861006400 |
[1,2,10,280,60060,85765680,2061378118800, 346915095471584640,1736278161426147413954880, 62144711688730139887005809020800, 103104526145243794108489566205445861006400] |