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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 21 |
| 3 | 201 |
| 4 | 2217 |
| 5 | 26535 |
| 6 | 335001 |
| 7 | 4391553 |
| 8 | 59203137 |
| 9 | 815580507 |
| 10 | 11430639165 |
| 11 | 162470033625 |
| 12 | 2336381642649 |
| 13 | 33930648153615 |
| 14 | 496935405133617 |
| 15 | 7331179445170689 |
| 16 | 108846406625097729 |
| 17 | 1625145134034548019 |
| 18 | 24385673680861258533 |
| 19 | 367546405595389076649 |
| 20 | 5561980053932228243529 |
[1,3,21,201,2217,26535,335001,4391553,59203137, 815580507,11430639165,162470033625,2336381642649, 33930648153615,496935405133617,7331179445170689, 108846406625097729,1625145134034548019, 24385673680861258533,367546405595389076649, 5561980053932228243529] |