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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | -5 |
| 2 | 6 |
| 3 | 2 |
| 4 | 6 |
| 5 | 18 |
| 6 | 66 |
| 7 | 278 |
| 8 | 1296 |
| 9 | 6528 |
| 10 | 34950 |
| 11 | 196578 |
| 12 | 1151610 |
| 13 | 6981102 |
| 14 | 43570170 |
| 15 | 278841438 |
| 16 | 1823991630 |
| 17 | 12162884778 |
| 18 | 82498605594 |
| 19 | 568140045918 |
| 20 | 3966323992074 |
| 21 | 28032955095198 |
| 22 | 200355706872054 |
| 23 | 1446628270673682 |
| 24 | 10542888272710224 |
| 25 | 77496225169484448 |
[1,-5,6,2,6,18,66,278,1296,6528,34950,196578, 1151610,6981102,43570170,278841438,1823991630, 12162884778,82498605594,568140045918, 3966323992074,28032955095198,200355706872054, 1446628270673682,10542888272710224, 77496225169484448] |