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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | -18 |
| 2 | -252 |
| 3 | -2376 |
| 4 | -19440 |
| 5 | -147744 |
| 6 | -1073088 |
| 7 | -7558272 |
| 8 | -52068096 |
| 9 | -352719360 |
| 10 | -2358180864 |
| 11 | -15600273408 |
| 12 | -102308769792 |
| 13 | -666095394816 |
| 14 | -4310029025280 |
| 15 | -27740914089984 |
| 16 | -177729924169728 |
| 17 | -1134086182797312 |
| 18 | -7210756923457536 |
[1,-18,-252,-2376,-19440,-147744,-1073088, -7558272,-52068096,-352719360,-2358180864, -15600273408,-102308769792,-666095394816, -4310029025280,-27740914089984,-177729924169728, -1134086182797312,-7210756923457536] |