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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 5 |
| 5 | 16 |
| 6 | 60 |
| 7 | 261 |
| 8 | 1243 |
| 9 | 6257 |
| 10 | 32721 |
| 11 | 175760 |
| 12 | 963900 |
| 13 | 5374400 |
| 14 | 30385256 |
| 15 | 173837631 |
| 16 | 1004867079 |
| 17 | 5861610475 |
| 18 | 34469014515 |
| 19 | 204161960310 |
| 20 | 1217145238485 |
| 21 | 7299007647552 |
| 22 | 44005602441840 |
[1,1,2,5,16,60,261,1243,6257,32721,175760,963900, 5374400,30385256,173837631,1004867079,5861610475, 34469014515,204161960310,1217145238485, 7299007647552,44005602441840] |