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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 84 |
| 3 | 504 |
| 4 | 1008 |
| 5 | 2016 |
| 6 | 4032 |
| 7 | 24192 |
| 8 | 12980362752 |
| 9 | 25960725504 |
| 10 | 1869172236288 |
[1,2,84,504,1008,2016,4032,24192,12980362752, 25960725504,1869172236288] |