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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | -1 |
| 2 | 3 |
| 3 | -7 |
| 4 | 39 |
| 5 | -31 |
| 6 | 1623 |
| 7 | 9953 |
| 8 | 182199 |
| 9 | 2116289 |
| 10 | 32269143 |
| 11 | 505278113 |
| 12 | 9743069559 |
| 13 | 214428606209 |
| 14 | 5156280298263 |
| 15 | 127321200213473 |
| 16 | 3176128419544119 |
| 17 | 80737907621585729 |
| 18 | 2147513299611040983 |
| 19 | 61423058495936864033 |
| 20 | 1912348969322283717879 |
| 21 | 64216042408215934910849 |
[1,-1,3,-7,39,-31,1623,9953,182199,2116289, 32269143,505278113,9743069559,214428606209, 5156280298263,127321200213473,3176128419544119, 80737907621585729,2147513299611040983, 61423058495936864033,1912348969322283717879, 64216042408215934910849] |