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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | -1 |
| 3 | -12 |
| 4 | 45 |
| 5 | 1920 |
| 6 | -12285 |
| 7 | -812160 |
| 8 | 7372665 |
| 9 | 675993600 |
| 10 | -7946069625 |
| 11 | -929719296000 |
| 12 | 13417865324325 |
| 13 | 1910208017203200 |
| 14 | -32683269859651125 |
| 15 | -5481709463273472000 |
| 16 | 108469408821131840625 |
| 17 | 20943691553556135936000 |
| 18 | -470506033739324534576625 |
| 19 | -102780474361885187112960000 |
[1,1,-1,-12,45,1920,-12285,-812160,7372665, 675993600,-7946069625,-929719296000, 13417865324325,1910208017203200, -32683269859651125,-5481709463273472000, 108469408821131840625,20943691553556135936000, -470506033739324534576625, -102780474361885187112960000] |