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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 9 |
| 4 | 30 |
| 5 | 104 |
| 6 | 374 |
| 7 | 1372 |
| 8 | 5121 |
| 9 | 19350 |
| 10 | 73820 |
| 11 | 283726 |
| 12 | 1097104 |
| 13 | 4262915 |
| 14 | 16630036 |
| 15 | 65090232 |
| 16 | 255470039 |
| 17 | 1005021759 |
| 18 | 3961596740 |
| 19 | 15642290396 |
| 20 | 61853211838 |
| 21 | 244889529931 |
| 22 | 970627733761 |
| 23 | 3850784072750 |
| 24 | 15290025210880 |
| 25 | 60755565168300 |
| 26 | 241571260582169 |
| 27 | 961066546034625 |
| 28 | 3825451487035020 |
[1,1,3,9,30,104,374,1372,5121,19350,73820,283726, 1097104,4262915,16630036,65090232,255470039, 1005021759,3961596740,15642290396,61853211838, 244889529931,970627733761,3850784072750, 15290025210880,60755565168300,241571260582169, 961066546034625,3825451487035020] |