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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 21 |
| 5 | 83 |
| 6 | 363 |
| 7 | 1730 |
| 8 | 8889 |
| 9 | 48829 |
| 10 | 284858 |
| 11 | 1755325 |
| 12 | 11374092 |
| 13 | 77208275 |
| 14 | 547261631 |
| 15 | 4039201624 |
| 16 | 30967330941 |
| 17 | 246084049137 |
| 18 | 2023030659970 |
| 19 | 17175765057532 |
| 20 | 150367445873108 |
| 21 | 1355528352031358 |
| 22 | 12566899017130088 |
[1,1,2,6,21,83,363,1730,8889,48829,284858,1755325, 11374092,77208275,547261631,4039201624, 30967330941,246084049137,2023030659970, 17175765057532,150367445873108,1355528352031358, 12566899017130088] |