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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 10 |
| 3 | 1680 |
| 4 | 5569200 |
| 5 | 426645273600 |
| 6 | 1135354270482432000 |
| 7 | 129053267560513803386880000 |
| 8 | 556394398742051964595520667648000000 |
| 9 | 99449133623220179596974346585642106880000000000 |
[1,10,1680,5569200,426645273600, 1135354270482432000,129053267560513803386880000, 556394398742051964595520667648000000, 99449133623220179596974346585642106880000000000] |