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| n | a(n) |
|---|---|
| 2 | 1 |
| 3 | 9 |
| 4 | 49 |
| 5 | 214 |
| 6 | 800 |
| 7 | 2685 |
| 8 | 8274 |
| 9 | 23829 |
| 10 | 64843 |
| 11 | 168223 |
| 12 | 418723 |
| 13 | 1005269 |
| 14 | 2337340 |
| 15 | 5281304 |
| 16 | 11629334 |
| 17 | 25015300 |
| 18 | 52670865 |
| 19 | 108745666 |
| 20 | 220489361 |
| 21 | 439619133 |
| 22 | 862952442 |
| 23 | 1669440245 |
| 24 | 3185892198 |
| 25 | 6002458625 |
| 26 | 11173532683 |
| 27 | 20564107275 |
[1,9,49,214,800,2685,8274,23829,64843,168223, 418723,1005269,2337340,5281304,11629334,25015300, 52670865,108745666,220489361,439619133,862952442, 1669440245,3185892198,6002458625,11173532683, 20564107275] |