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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | -1 |
| 3 | 7 |
| 4 | -24 |
| 5 | 215 |
| 6 | -1515 |
| 7 | 16721 |
| 8 | -176568 |
| 9 | 2363165 |
| 10 | -32662125 |
| 11 | 521810859 |
| 12 | -8824531056 |
| 13 | 165050184611 |
| 14 | -3283420714119 |
| 15 | 70591429387077 |
| 16 | -1610563051907280 |
| 17 | 39183483858949049 |
| 18 | -1007242998864835257 |
[0,1,-1,7,-24,215,-1515,16721,-176568,2363165, -32662125,521810859,-8824531056,165050184611, -3283420714119,70591429387077,-1610563051907280, 39183483858949049,-1007242998864835257] |