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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 3 |
| 4 | 5 |
| 5 | -6 |
| 6 | -11 |
| 7 | -18 |
| 8 | -33 |
| 9 | -61 |
| 10 | 66 |
| 11 | 126 |
| 12 | 198 |
| 13 | 241 |
| 14 | 378 |
| 15 | -522 |
| 16 | 723 |
| 17 | -762 |
| 18 | -1017 |
| 19 | -1176 |
[1,2,3,5,-6,-11,-18,-33,-61,66,126,198,241,378, -522,723,-762,-1017,-1176] |