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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 27 |
| 3 | 283 |
| 4 | 4217 |
| 5 | 82971 |
| 6 | 2041855 |
| 7 | 60475885 |
| 8 | 2096566449 |
| 9 | 83324680435 |
| 10 | 3736041351311 |
| 11 | 186594364199277 |
| 12 | 10274269171279657 |
| 13 | 618386703880855339 |
| 14 | 40393224245061185919 |
| 15 | 2846030947359659421901 |
| 16 | 215160957844217080056161 |
| 17 | 17373449685399138641312739 |
| 18 | 1492298627191467511376377999 |
[1,4,27,283,4217,82971,2041855,60475885, 2096566449,83324680435,3736041351311, 186594364199277,10274269171279657, 618386703880855339,40393224245061185919, 2846030947359659421901,215160957844217080056161, 17373449685399138641312739, 1492298627191467511376377999] |