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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 560 |
| 4 | 189688 |
| 5 | 264895640 |
| 6 | 1770631206422 |
| 7 | 2903212163753000 |
| 8 | 6132937892156709562 |
[0,0,560,189688,264895640,1770631206422, 2903212163753000,6132937892156709562] |