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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 9 |
| 4 | 26 |
| 5 | 68 |
| 6 | 198 |
| 7 | 536 |
| 8 | 1660 |
| 9 | 4769 |
| 10 | 15945 |
| 11 | 46240 |
| 12 | 165732 |
| 13 | 488268 |
| 14 | 1848866 |
| 15 | 5852344 |
[1,3,9,26,68,198,536,1660,4769,15945,46240,165732, 488268,1848866,5852344] |