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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 9 |
| 4 | 33 |
| 5 | 127 |
| 6 | 519 |
| 7 | 2191 |
| 8 | 9509 |
| 9 | 42109 |
| 10 | 189571 |
| 11 | 864865 |
| 12 | 3989877 |
| 13 | 18580355 |
| 14 | 87227311 |
| 15 | 412371551 |
| 16 | 1961485449 |
| 17 | 9380593513 |
| 18 | 45078031763 |
| 19 | 217555637193 |
| 20 | 1054048424377 |
| 21 | 5124790576295 |
| 22 | 24996499042775 |
| 23 | 122278420437071 |
[1,1,3,9,33,127,519,2191,9509,42109,189571,864865, 3989877,18580355,87227311,412371551,1961485449, 9380593513,45078031763,217555637193,1054048424377, 5124790576295,24996499042775,122278420437071] |