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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 10 |
| 3 | 250 |
| 4 | 22500 |
| 5 | 2788800 |
| 6 | 1002405600 |
| 7 | 359463283200 |
| 8 | 326108342112000 |
| 9 | 257963213378304000 |
[1,10,250,22500,2788800,1002405600,359463283200, 326108342112000,257963213378304000] |