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| n | a(n) |
|---|---|
| 1 | -1 |
| 2 | 64 |
| 3 | -207360000 |
| 4 | 15161366937600000000 |
| 5 | -16026514807440384000000000000000000000000 |
| 6 | 9186394651457723405912022826165758590976000000000000000000000000 |
[-1,64,-207360000,15161366937600000000, -16026514807440384000000000000000000000000, 91863946514577234059120228261657585909760000000000\ 00000000000000] |