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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 9 |
| 3 | 30 |
| 4 | 106 |
| 5 | 348 |
| 6 | 1153 |
| 7 | 3698 |
| 8 | 11798 |
| 9 | 37034 |
| 10 | 115294 |
| 11 | 355202 |
| 12 | 1086080 |
| 13 | 3294912 |
| 14 | 9931019 |
| 15 | 29745296 |
| 16 | 88597104 |
| 17 | 262508288 |
| 18 | 774073787 |
| 19 | 2272321666 |
| 20 | 6642701371 |
| 21 | 19342768210 |
| 22 | 56117550874 |
| 23 | 162247236638 |
| 24 | 467563212923 |
| 25 | 1343273262184 |
| 26 | 3847866714452 |
| 27 | 10991864363660 |
[1,2,9,30,106,348,1153,3698,11798,37034,115294, 355202,1086080,3294912,9931019,29745296,88597104, 262508288,774073787,2272321666,6642701371, 19342768210,56117550874,162247236638,467563212923, 1343273262184,3847866714452,10991864363660] |