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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 17 |
| 5 | 7720 |
| 6 | 4829792 |
| 7 | 6716752296 |
| 8 | 25512182673851 |
| 9 | 280268522844817397 |
| 10 | 9139496699518220983774 |
| 11 | 891049711767000782484301987 |
[0,0,0,17,7720,4829792,6716752296,25512182673851, 280268522844817397,9139496699518220983774, 891049711767000782484301987] |