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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 19 |
| 4 | 59 |
| 5 | 183 |
| 6 | 568 |
| 7 | 1763 |
| 8 | 5472 |
| 9 | 16984 |
| 10 | 52715 |
| 11 | 163617 |
| 12 | 507835 |
| 13 | 1576220 |
| 14 | 4892277 |
| 15 | 15184666 |
| 16 | 47130218 |
| 17 | 146282931 |
| 18 | 454033459 |
| 19 | 1409230595 |
| 20 | 4373974716 |
| 21 | 13575957607 |
| 22 | 42137103416 |
| 23 | 130785284964 |
| 24 | 405931812499 |
| 25 | 1259932540913 |
| 26 | 3910582907703 |
| 27 | 12137680535608 |
[1,2,6,19,59,183,568,1763,5472,16984,52715,163617, 507835,1576220,4892277,15184666,47130218, 146282931,454033459,1409230595,4373974716, 13575957607,42137103416,130785284964,405931812499, 1259932540913,3910582907703,12137680535608] |