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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 3 |
| 6 | 9 |
| 7 | 27 |
| 8 | 85 |
| 9 | 337 |
| 10 | 1791 |
| 11 | 13253 |
| 12 | 115267 |
| 13 | 1169733 |
| 14 | 14374957 |
| 15 | 216583105 |
| 16 | 4102635811 |
| 17 | 98419728413 |
| 18 | 2904752917775 |
| 19 | 103834255604223 |
| 20 | 4525458320487677 |
[1,1,1,1,3,9,27,85,337,1791,13253,115267,1169733, 14374957,216583105,4102635811,98419728413, 2904752917775,103834255604223,4525458320487677] |