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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 5 |
| 3 | 18 |
| 4 | 67 |
| 5 | 265 |
| 6 | 1099 |
| 7 | 4615 |
| 8 | 19918 |
| 9 | 86872 |
| 10 | 384831 |
| 11 | 1723134 |
| 12 | 7782492 |
| 13 | 35456485 |
| 14 | 162474523 |
| 15 | 749303875 |
| 16 | 3471551664 |
| 17 | 16159342707 |
| 18 | 75510910742 |
| 19 | 354110285481 |
| 20 | 1666053933555 |
| 21 | 7860810672910 |
| 22 | 37190149979929 |
| 23 | 176363094591082 |
| 24 | 838240103613605 |
| 25 | 3992076916379348 |
| 26 | 19048084412644487 |
| 27 | 91045079127716986 |
[1,2,5,18,67,265,1099,4615,19918,86872,384831, 1723134,7782492,35456485,162474523,749303875, 3471551664,16159342707,75510910742,354110285481, 1666053933555,7860810672910,37190149979929, 176363094591082,838240103613605,3992076916379348, 19048084412644487,91045079127716986] |