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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | -1 |
| 3 | -1 |
| 4 | 17 |
| 5 | -95 |
| 6 | 175 |
| 7 | 3775 |
| 8 | -63775 |
| 9 | 533825 |
| 10 | 108575 |
| 11 | -98151425 |
| 12 | 2037293425 |
| 13 | -20945772575 |
| 14 | -111991234225 |
| 15 | 10648024541375 |
| 16 | -261756393325375 |
| 17 | 3003396413226625 |
| 18 | 43283396332525375 |
| 19 | -3352997476533082625 |
| 20 | 94455063540276700625 |
| 21 | -1135469395905648529375 |
[1,1,-1,-1,17,-95,175,3775,-63775,533825,108575, -98151425,2037293425,-20945772575,-111991234225, 10648024541375,-261756393325375,3003396413226625, 43283396332525375,-3352997476533082625, 94455063540276700625,-1135469395905648529375] |