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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 252 |
| 3 | 756756 |
| 4 | 11732745024 |
| 5 | 52977847995072 |
| 6 | 131319696504676680 |
| 7 | 302061042944500510428 |
| 8 | 847432462636241316703042 |
[1,1,252,756756,11732745024,52977847995072, 131319696504676680,302061042944500510428, 847432462636241316703042] |