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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | -3 |
| 3 | 2 |
| 4 | -3 |
| 5 | 6 |
| 6 | -11 |
| 7 | 18 |
| 8 | -30 |
| 9 | 56 |
| 10 | -105 |
| 11 | 186 |
| 12 | -335 |
| 13 | 630 |
| 14 | -1179 |
| 15 | 2182 |
| 16 | -4080 |
| 17 | 7710 |
| 18 | -14588 |
| 19 | 27594 |
| 20 | -52377 |
| 21 | 99858 |
| 22 | -190743 |
| 23 | 364722 |
| 24 | -698870 |
| 25 | 1342176 |
| 26 | -2581425 |
| 27 | 4971008 |
| 28 | -9586395 |
| 29 | 18512790 |
| 30 | -35792449 |
| 31 | 69273666 |
| 32 | -134215680 |
| 33 | 260300986 |
[2,-3,2,-3,6,-11,18,-30,56,-105,186,-335,630, -1179,2182,-4080,7710,-14588,27594,-52377,99858, -190743,364722,-698870,1342176,-2581425,4971008, -9586395,18512790,-35792449,69273666,-134215680, 260300986] |