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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 11 |
| 4 | 55 |
| 5 | 339 |
| 6 | 2499 |
| 7 | 21433 |
| 8 | 209717 |
| 9 | 2305719 |
| 10 | 28141925 |
| 11 | 377579731 |
| 12 | 5523750291 |
| 13 | 87508680045 |
| 14 | 1492510215135 |
| 15 | 27266981038343 |
| 16 | 531245913925837 |
| 17 | 10995334516297279 |
| 18 | 240925208376757203 |
| 19 | 5571653169126500083 |
| 20 | 135617881389268715939 |
| 21 | 3465772763274106884733 |
[1,1,3,11,55,339,2499,21433,209717,2305719, 28141925,377579731,5523750291,87508680045, 1492510215135,27266981038343,531245913925837, 10995334516297279,240925208376757203, 5571653169126500083,135617881389268715939, 3465772763274106884733] |