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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 66 |
| 3 | 16104 |
| 4 | 16506600 |
| 5 | 51599631600 |
| 6 | 401290334953200 |
| 7 | 6744887949893385600 |
| 8 | 221023233230056352726400 |
| 9 | 13051421922234827628493920000 |
| 10 | 1305155243645404997677020493920000 |
| 11 | 210197862299579765685879504586803840000 |
| 12 | 52304164669591331834914454764848159918720000 |
[1,2,66,16104,16506600,51599631600, 401290334953200,6744887949893385600, 221023233230056352726400, 13051421922234827628493920000, 1305155243645404997677020493920000, 210197862299579765685879504586803840000, 52304164669591331834914454764848159918720000] |