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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 22 |
| 5 | 87 |
| 6 | 351 |
| 7 | 1416 |
| 8 | 5681 |
| 9 | 22660 |
| 10 | 89961 |
| 11 | 355924 |
| 12 | 1404839 |
| 13 | 5536143 |
| 14 | 21794634 |
| 15 | 85749490 |
| 16 | 337271186 |
| 17 | 1326421512 |
| 18 | 5216761708 |
| 19 | 20520185594 |
| 20 | 80733298320 |
| 21 | 317713643536 |
| 22 | 1250674963766 |
| 23 | 4924782835110 |
| 24 | 19398524629494 |
| 25 | 76434881013402 |
| 26 | 301270165265954 |
[1,1,2,6,22,87,351,1416,5681,22660,89961,355924, 1404839,5536143,21794634,85749490,337271186, 1326421512,5216761708,20520185594,80733298320, 317713643536,1250674963766,4924782835110, 19398524629494,76434881013402,301270165265954] |