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| n | a(n) |
|---|---|
| 4 | -61 |
| 5 | -235 |
| 6 | 810 |
| 7 | 38850 |
| 8 | 757680 |
| 9 | 12836880 |
| 10 | 212133600 |
| 11 | 3554258400 |
| 12 | 61372080000 |
| 13 | 1100366467200 |
| 14 | 20555914579200 |
| 15 | 400638734496000 |
| 16 | 8148554878464000 |
| 17 | 172878910364160000 |
| 18 | 3823017399032832000 |
| 19 | 88035572875041792000 |
| 20 | 2108819186504110080000 |
[-61,-235,810,38850,757680,12836880,212133600, 3554258400,61372080000,1100366467200, 20555914579200,400638734496000,8148554878464000, 172878910364160000,3823017399032832000, 88035572875041792000,2108819186504110080000] |