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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 22 |
| 5 | 96 |
| 6 | 492 |
| 7 | 2902 |
| 8 | 19350 |
| 9 | 143918 |
| 10 | 1181540 |
| 11 | 10614698 |
| 12 | 103589738 |
| 13 | 1091367634 |
| 14 | 12346368424 |
| 15 | 149276823258 |
| 16 | 1921099070062 |
| 17 | 26220186000950 |
| 18 | 378308908684300 |
| 19 | 5753387612678314 |
| 20 | 91988260677198002 |
| 21 | 1542570178562361018 |
| 22 | 27072325866355742048 |
[1,1,2,6,22,96,492,2902,19350,143918,1181540, 10614698,103589738,1091367634,12346368424, 149276823258,1921099070062,26220186000950, 378308908684300,5753387612678314, 91988260677198002,1542570178562361018, 27072325866355742048] |