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| n | a(n) |
|---|---|
| 4 | 1 |
| 5 | -96 |
| 6 | 4464 |
| 7 | -133760 |
| 8 | 2897880 |
| 9 | -48264768 |
| 10 | 641207744 |
| 11 | -6954435840 |
| 12 | 62452035180 |
| 13 | -467536231520 |
| 14 | 2916146241888 |
| 15 | -14993052561792 |
| 16 | 61695767581248 |
| 17 | -187599812159040 |
| 18 | 302907998183040 |
| 19 | 676931170946304 |
| 20 | -7255673126427378 |
| 21 | 28908305661771648 |
[1,-96,4464,-133760,2897880,-48264768,641207744, -6954435840,62452035180,-467536231520, 2916146241888,-14993052561792,61695767581248, -187599812159040,302907998183040,676931170946304, -7255673126427378,28908305661771648] |