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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 15 |
| 5 | 51 |
| 6 | 191 |
| 7 | 773 |
| 8 | 3336 |
| 9 | 15207 |
| 10 | 72697 |
| 11 | 362447 |
| 12 | 1876392 |
| 13 | 10051083 |
| 14 | 55544661 |
| 15 | 315899245 |
| 16 | 1845139684 |
| 17 | 11048651523 |
| 18 | 67719859612 |
| 19 | 424287619507 |
| 20 | 2714074517843 |
| 21 | 17706680249505 |
| 22 | 117704101959444 |
| 23 | 796546613501759 |
| 24 | 5483490237025393 |
| 25 | 38372546811580251 |
[1,1,2,5,15,51,191,773,3336,15207,72697,362447, 1876392,10051083,55544661,315899245,1845139684, 11048651523,67719859612,424287619507, 2714074517843,17706680249505,117704101959444, 796546613501759,5483490237025393, 38372546811580251] |