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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | -2 |
| 3 | 4 |
| 4 | -16 |
| 5 | 96 |
| 6 | -576 |
| 7 | 3760 |
| 8 | -30080 |
| 9 | 278656 |
| 10 | -2786560 |
| 11 | 30298368 |
| 12 | -363580416 |
| 13 | 4748913664 |
| 14 | -66484791296 |
| 15 | 995368112128 |
| 16 | -15925889794048 |
| 17 | 270949991841792 |
| 18 | -4877099853152256 |
| 19 | 92635808324780032 |
| 20 | -1852716166495600640 |
[0,1,-2,4,-16,96,-576,3760,-30080,278656,-2786560, 30298368,-363580416,4748913664,-66484791296, 995368112128,-15925889794048,270949991841792, -4877099853152256,92635808324780032, -1852716166495600640] |