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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 9 |
| 4 | 31 |
| 5 | 113 |
| 6 | 429 |
| 7 | 1681 |
| 8 | 6739 |
| 9 | 27523 |
| 10 | 114093 |
| 11 | 478843 |
| 12 | 2030689 |
| 13 | 8688595 |
| 14 | 37461651 |
| 15 | 162604083 |
| 16 | 709963053 |
| 17 | 3116099485 |
| 18 | 13740924463 |
| 19 | 60847717965 |
| 20 | 270470978627 |
| 21 | 1206406375485 |
| 22 | 5397984469009 |
| 23 | 24222544060981 |
[1,1,3,9,31,113,429,1681,6739,27523,114093,478843, 2030689,8688595,37461651,162604083,709963053, 3116099485,13740924463,60847717965,270470978627, 1206406375485,5397984469009,24222544060981] |