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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | -1 |
| 3 | -2 |
| 4 | -3 |
| 5 | -5 |
| 6 | -9 |
| 7 | -32 |
| 8 | -56 |
| 9 | -117 |
| 10 | -315 |
| 11 | -1458 |
| 12 | -2673 |
| 13 | -7776 |
| 14 | -22386 |
| 15 | -131072 |
[0,-1,-2,-3,-5,-9,-32,-56,-117,-315,-1458,-2673, -7776,-22386,-131072] |