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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 3 |
| 5 | 6 |
| 6 | 21 |
| 7 | 75 |
| 8 | 415 |
| 9 | 2621 |
| 10 | 21066 |
| 11 | 195485 |
| 12 | 2083543 |
| 13 | 24744474 |
| 14 | 323438322 |
| 15 | 4596672672 |
| 16 | 70440521310 |
[1,1,1,3,6,21,75,415,2621,21066,195485,2083543, 24744474,323438322,4596672672,70440521310] |