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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 12 |
| 5 | 27 |
| 6 | 84 |
| 7 | 224 |
| 8 | 712 |
| 9 | 2006 |
| 10 | 6662 |
| 11 | 19530 |
| 12 | 66075 |
| 13 | 200809 |
| 14 | 687115 |
| 15 | 2142561 |
| 16 | 7425605 |
| 17 | 23578903 |
| 18 | 82400432 |
| 19 | 266087903 |
| 20 | 936840796 |
| 21 | 3062357204 |
| 22 | 10851189800 |
| 23 | 35873694160 |
| 24 | 127705408346 |
| 25 | 426238811147 |
| 26 | 1524384589614 |
| 27 | 5127606562685 |
| 28 | 18409111458399 |
| 29 | 62372449364233 |
| 30 | 224664598203130 |
| 31 | 765864853776425 |
[1,1,2,4,12,27,84,224,712,2006,6662,19530,66075, 200809,687115,2142561,7425605,23578903,82400432, 266087903,936840796,3062357204,10851189800, 35873694160,127705408346,426238811147, 1524384589614,5127606562685,18409111458399, 62372449364233,224664598203130,765864853776425] |