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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 30 |
| 3 | 720 |
| 4 | 53505 |
| 5 | 12680820 |
| 6 | 9936894780 |
| 7 | 26516959720695 |
| 8 | 246350237314954005 |
| 9 | 8100725881546916639370 |
| 10 | 954991817788505196528852930 |
| 11 | 407790975833063512191532123109595 |
[4,30,720,53505,12680820,9936894780, 26516959720695,246350237314954005, 8100725881546916639370, 954991817788505196528852930, 407790975833063512191532123109595] |