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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | -1 |
| 2 | 5 |
| 3 | -1 |
| 4 | 29 |
| 5 | 23 |
| 6 | 197 |
| 7 | 335 |
| 8 | 1517 |
| 9 | 3527 |
| 10 | 12629 |
| 11 | 33791 |
| 12 | 109565 |
| 13 | 312311 |
| 14 | 969701 |
| 15 | 2843567 |
| 16 | 8661773 |
| 17 | 25723175 |
| 18 | 77693813 |
| 19 | 232032863 |
| 20 | 698195741 |
| 21 | 2090392919 |
| 22 | 6279567365 |
| 23 | 18821924879 |
| 24 | 56499329069 |
| 25 | 169430878343 |
| 26 | 508426852757 |
| 27 | 1525012122815 |
| 28 | 4575573239357 |
[1,-1,5,-1,29,23,197,335,1517,3527,12629,33791, 109565,312311,969701,2843567,8661773,25723175, 77693813,232032863,698195741,2090392919, 6279567365,18821924879,56499329069,169430878343, 508426852757,1525012122815,4575573239357] |