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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | -1 |
| 3 | 3 |
| 4 | -13 |
| 5 | 77 |
| 6 | -576 |
| 7 | 5219 |
| 8 | -55567 |
| 9 | 680028 |
| 10 | -9405302 |
| 11 | 145067040 |
| 12 | -2468571128 |
| 13 | 45936991110 |
| 14 | -927915150852 |
| 15 | 20219040931738 |
| 16 | -472697857817078 |
| 17 | 11801903989774760 |
| 18 | -313395752536945568 |
| 19 | 8819464678850030936 |
| 20 | -262185434197432956664 |
| 21 | 8210080944919085511680 |
[1,-1,3,-13,77,-576,5219,-55567,680028,-9405302, 145067040,-2468571128,45936991110,-927915150852, 20219040931738,-472697857817078,11801903989774760, -313395752536945568,8819464678850030936, -262185434197432956664,8210080944919085511680] |