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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | -4 |
| 2 | 9 |
| 3 | -24 |
| 4 | 69 |
| 5 | -204 |
| 6 | 609 |
| 7 | -1824 |
| 8 | 5469 |
| 9 | -16404 |
| 10 | 49209 |
| 11 | -147624 |
| 12 | 442869 |
| 13 | -1328604 |
| 14 | 3985809 |
| 15 | -11957424 |
| 16 | 35872269 |
| 17 | -107616804 |
| 18 | 322850409 |
| 19 | -968551224 |
| 20 | 2905653669 |
| 21 | -8716961004 |
| 22 | 26150883009 |
| 23 | -78452649024 |
| 24 | 235357947069 |
| 25 | -706073841204 |
| 26 | 2118221523609 |
[1,-4,9,-24,69,-204,609,-1824,5469,-16404,49209, -147624,442869,-1328604,3985809,-11957424, 35872269,-107616804,322850409,-968551224, 2905653669,-8716961004,26150883009,-78452649024, 235357947069,-706073841204,2118221523609] |