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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 3 |
| 3 | 11 |
| 4 | 33 |
| 5 | 96 |
| 6 | 278 |
| 7 | 787 |
| 8 | 2205 |
| 9 | 6133 |
| 10 | 16941 |
| 11 | 46554 |
| 12 | 127390 |
| 13 | 347331 |
| 14 | 944121 |
| 15 | 2559607 |
| 16 | 6923529 |
| 17 | 18690138 |
| 18 | 50364988 |
| 19 | 135506485 |
| 20 | 364063815 |
| 21 | 976880631 |
| 22 | 2618206923 |
| 23 | 7009868646 |
| 24 | 18749876418 |
| 25 | 50107633501 |
| 26 | 133800148323 |
| 27 | 357012426677 |
| 28 | 951936494055 |
[0,1,3,11,33,96,278,787,2205,6133,16941,46554, 127390,347331,944121,2559607,6923529,18690138, 50364988,135506485,364063815,976880631,2618206923, 7009868646,18749876418,50107633501,133800148323, 357012426677,951936494055] |