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| n | a(n) |
|---|---|
| 1 | 3 |
| 2 | 1 |
| 3 | 1 |
| 4 | 3 |
| 5 | 9 |
| 6 | 27 |
| 7 | 84 |
| 8 | 261 |
| 9 | 810 |
| 10 | 2514 |
| 11 | 8046 |
| 12 | 25704 |
| 13 | 81975 |
| 14 | 261261 |
| 15 | 854037 |
| 16 | 2784540 |
| 17 | 9057393 |
| 18 | 29439855 |
| 19 | 97650930 |
| 20 | 323099676 |
| 21 | 1066565907 |
| 22 | 3517004046 |
| 23 | 11791407663 |
| 24 | 39431809098 |
| 25 | 131550859650 |
| 26 | 438453827928 |
| 27 | 1481254263945 |
| 28 | 4993010577093 |
[3,1,1,3,9,27,84,261,810,2514,8046,25704,81975, 261261,854037,2784540,9057393,29439855,97650930, 323099676,1066565907,3517004046,11791407663, 39431809098,131550859650,438453827928, 1481254263945,4993010577093] |