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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 4 |
| 4 | 21 |
| 5 | 131 |
| 6 | 914 |
| 7 | 6910 |
| 8 | 55477 |
| 9 | 466729 |
| 10 | 4076430 |
| 11 | 36712325 |
| 12 | 339195058 |
| 13 | 3202515525 |
| 14 | 30803440806 |
| 15 | 301094270964 |
| 16 | 2984903334517 |
| 17 | 29961600364523 |
| 18 | 304094354787062 |
| 19 | 3117138919265903 |
| 20 | 32238856059792302 |
| 21 | 336132907436386486 |
| 22 | 3530470987229030696 |
| 23 | 37330864330583904876 |
| 24 | 397168915877285183906 |
[1,1,1,4,21,131,914,6910,55477,466729,4076430, 36712325,339195058,3202515525,30803440806, 301094270964,2984903334517,29961600364523, 304094354787062,3117138919265903, 32238856059792302,336132907436386486, 3530470987229030696,37330864330583904876, 397168915877285183906] |