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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 11 |
| 4 | 52 |
| 5 | 170 |
| 6 | 820 |
| 7 | 2959 |
| 8 | 14514 |
| 9 | 55611 |
| 10 | 274519 |
| 11 | 1091963 |
| 12 | 5413275 |
| 13 | 22125974 |
| 14 | 109968669 |
| 15 | 458527130 |
| 16 | 2282677742 |
| 17 | 9666067566 |
| 18 | 48176053055 |
| 19 | 206527439304 |
| 20 | 1030152690801 |
| 21 | 4460625399845 |
| 22 | 22262288594871 |
| 23 | 97203545438273 |
| 24 | 485331216939480 |
| 25 | 2134048347102848 |
| 26 | 10658501929003342 |
| 27 | 47149574060250334 |
[1,1,4,11,52,170,820,2959,14514,55611,274519, 1091963,5413275,22125974,109968669,458527130, 2282677742,9666067566,48176053055,206527439304, 1030152690801,4460625399845,22262288594871, 97203545438273,485331216939480,2134048347102848, 10658501929003342,47149574060250334] |