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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | -1 |
| 3 | 2 |
| 4 | -6 |
| 5 | 20 |
| 6 | -80 |
| 7 | 348 |
| 8 | -1778 |
| 9 | 9892 |
| 10 | -64392 |
| 11 | 449596 |
| 12 | -3609782 |
| 13 | 30152616 |
| 14 | -284037468 |
| 15 | 2694480888 |
| 16 | -28592860322 |
| 17 | 295151311376 |
| 18 | -3440953545088 |
| 19 | 37165311149276 |
| 20 | -471576198145144 |
| 21 | 5062381083026352 |
| 22 | -71104461751595892 |
[1,-1,2,-6,20,-80,348,-1778,9892,-64392,449596, -3609782,30152616,-284037468,2694480888, -28592860322,295151311376,-3440953545088, 37165311149276,-471576198145144,5062381083026352, -71104461751595892] |