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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 4 |
| 3 | -6 |
| 4 | 91 |
| 5 | -470 |
| 6 | 6100 |
| 7 | -57225 |
| 8 | 822065 |
| 9 | -11044260 |
| 10 | 184836950 |
| 11 | -3164767375 |
| 12 | 61845881375 |
| 13 | -1272676666950 |
| 14 | 28707736665400 |
| 15 | -686107336312125 |
| 16 | 17613438383958625 |
| 17 | -478324499820401000 |
| 18 | 13791544596522540250 |
[1,0,4,-6,91,-470,6100,-57225,822065,-11044260, 184836950,-3164767375,61845881375,-1272676666950, 28707736665400,-686107336312125,17613438383958625, -478324499820401000,13791544596522540250] |