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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 9 |
| 4 | 30 |
| 5 | 100 |
| 6 | 358 |
| 7 | 1274 |
| 8 | 4696 |
| 9 | 17271 |
| 10 | 64812 |
| 11 | 243124 |
| 12 | 923171 |
| 13 | 3507259 |
| 14 | 13429612 |
| 15 | 51468323 |
| 16 | 198303497 |
| 17 | 764804869 |
| 18 | 2960762145 |
| 19 | 11473325435 |
| 20 | 44582616732 |
| 21 | 173402227469 |
| 22 | 675831532852 |
| 23 | 2636356555098 |
| 24 | 10300561261380 |
| 25 | 40277734329466 |
| 26 | 157694323974257 |
| 27 | 617846137124040 |
| 28 | 2423186102532487 |
[1,1,3,9,30,100,358,1274,4696,17271,64812,243124, 923171,3507259,13429612,51468323,198303497, 764804869,2960762145,11473325435,44582616732, 173402227469,675831532852,2636356555098, 10300561261380,40277734329466,157694323974257, 617846137124040,2423186102532487] |