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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | -1 |
| 2 | -1 |
| 3 | -55 |
| 4 | 217 |
| 5 | -2441 |
| 6 | 41911 |
| 7 | -343519 |
| 8 | 10531025 |
| 9 | -123024817 |
| 10 | 2722259791 |
| 11 | -64395229031 |
| 12 | 1218005521129 |
| 13 | -36874422541945 |
| 14 | 785879799954887 |
| 15 | -25331247487596751 |
| 16 | 708096286059632161 |
| 17 | -21422225147712360929 |
| 18 | 741754828422824400415 |
[1,-1,-1,-55,217,-2441,41911,-343519,10531025, -123024817,2722259791,-64395229031,1218005521129, -36874422541945,785879799954887, -25331247487596751,708096286059632161, -21422225147712360929,741754828422824400415] |