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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | -18 |
| 2 | -108 |
| 3 | -936 |
| 4 | -13194 |
| 5 | -224424 |
| 6 | -4218264 |
| 7 | -84318336 |
| 8 | -1759467636 |
| 9 | -37903487130 |
| 10 | -836893437912 |
| 11 | -18844318997496 |
| 12 | -431163494289720 |
| 13 | -9997357777073064 |
| 14 | -234430475682110256 |
| 15 | -5550426839122171776 |
| 16 | -132513976699508759994 |
[1,-18,-108,-936,-13194,-224424,-4218264, -84318336,-1759467636,-37903487130,-836893437912, -18844318997496,-431163494289720, -9997357777073064,-234430475682110256, -5550426839122171776,-132513976699508759994] |