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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 5 |
| 3 | 16 |
| 4 | 69 |
| 5 | 386 |
| 6 | 2665 |
| 7 | 21856 |
| 8 | 207369 |
| 9 | 2233346 |
| 10 | 26910637 |
| 11 | 358654640 |
| 12 | 5238083085 |
| 13 | 83187634306 |
| 14 | 1427274447313 |
| 15 | 26308754113344 |
| 16 | 518495885082513 |
| 17 | 10879652226044546 |
| 18 | 242157991346605909 |
| 19 | 5698578388375932368 |
| 20 | 141364265347273219925 |
| 21 | 3686958817004484491522 |
[1,2,5,16,69,386,2665,21856,207369,2233346, 26910637,358654640,5238083085,83187634306, 1427274447313,26308754113344,518495885082513, 10879652226044546,242157991346605909, 5698578388375932368,141364265347273219925, 3686958817004484491522] |