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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 7 |
| 3 | 21 |
| 4 | 82 |
| 5 | 295 |
| 6 | 1224 |
| 7 | 4863 |
| 8 | 20642 |
| 9 | 86712 |
| 10 | 375745 |
| 11 | 1636141 |
| 12 | 7224851 |
| 13 | 32128224 |
| 14 | 144099952 |
| 15 | 650284953 |
| 16 | 2955045582 |
| 17 | 13489230967 |
| 18 | 61907970108 |
| 19 | 285216533074 |
| 20 | 1319432538352 |
| 21 | 6125687837276 |
| 22 | 28528343584820 |
| 23 | 133271278318064 |
| 24 | 624219798528028 |
| 25 | 2931203273847741 |
| 26 | 13797068728422039 |
| 27 | 65078551899506782 |
[1,2,7,21,82,295,1224,4863,20642,86712,375745, 1636141,7224851,32128224,144099952,650284953, 2955045582,13489230967,61907970108,285216533074, 1319432538352,6125687837276,28528343584820, 133271278318064,624219798528028,2931203273847741, 13797068728422039,65078551899506782] |