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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 9 |
| 3 | 28 |
| 4 | 88 |
| 5 | 276 |
| 6 | 867 |
| 7 | 2724 |
| 8 | 8558 |
| 9 | 26886 |
| 10 | 84465 |
| 11 | 265355 |
| 12 | 833637 |
| 13 | 2618948 |
| 14 | 8227668 |
| 15 | 25847981 |
| 16 | 81203827 |
| 17 | 255109346 |
| 18 | 801449647 |
| 19 | 2517828323 |
| 20 | 7909990963 |
| 21 | 24849969499 |
| 22 | 78068481620 |
| 23 | 245259368334 |
| 24 | 770505029782 |
| 25 | 2420612941117 |
[1,3,9,28,88,276,867,2724,8558,26886,84465,265355, 833637,2618948,8227668,25847981,81203827, 255109346,801449647,2517828323,7909990963, 24849969499,78068481620,245259368334,770505029782, 2420612941117] |