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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 1 |
| 6 | 3 |
| 7 | 7 |
| 8 | 13 |
| 9 | 39 |
| 10 | 123 |
| 11 | 461 |
| 12 | 2371 |
| 13 | 13249 |
| 14 | 80863 |
| 15 | 611487 |
| 16 | 5648891 |
| 17 | 61162833 |
| 18 | 795442861 |
| 19 | 12190308735 |
| 20 | 215424452659 |
[1,1,1,1,1,3,7,13,39,123,461,2371,13249,80863, 611487,5648891,61162833,795442861,12190308735, 215424452659] |