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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 3 |
| 3 | 9 |
| 4 | 28 |
| 5 | 88 |
| 6 | 278 |
| 7 | 873 |
| 8 | 2742 |
| 9 | 8616 |
| 10 | 27067 |
| 11 | 85032 |
| 12 | 267137 |
| 13 | 839237 |
| 14 | 2636540 |
| 15 | 8282934 |
| 16 | 26021606 |
| 17 | 81749286 |
| 18 | 256822958 |
| 19 | 806833117 |
| 20 | 2534740992 |
| 21 | 7963123679 |
| 22 | 25016890851 |
| 23 | 78592880513 |
| 24 | 246906816043 |
| 25 | 775680639401 |
| 26 | 2436872598275 |
| 27 | 7655661052475 |
| 28 | 24050968520829 |
[0,1,3,9,28,88,278,873,2742,8616,27067,85032, 267137,839237,2636540,8282934,26021606,81749286, 256822958,806833117,2534740992,7963123679, 25016890851,78592880513,246906816043,775680639401, 2436872598275,7655661052475,24050968520829] |