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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 6 |
| 2 | 18 |
| 3 | 54 |
| 4 | 162 |
| 5 | 474 |
| 6 | 1398 |
| 7 | 4074 |
| 8 | 11898 |
| 9 | 34554 |
| 10 | 100302 |
| 11 | 290334 |
| 12 | 839466 |
[1,6,18,54,162,474,1398,4074,11898,34554,100302, 290334,839466] |