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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | -1 |
| 2 | 7 |
| 3 | -31 |
| 4 | 127 |
| 5 | -2555 |
| 6 | 1414477 |
| 7 | -57337 |
| 8 | 118518239 |
| 9 | -5749691557 |
| 10 | 91546277357 |
[1,-1,7,-31,127,-2555,1414477,-57337,118518239, -5749691557,91546277357] |