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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 8 |
| 5 | 24 |
| 6 | 126 |
| 7 | 316 |
| 8 | 1344 |
| 9 | 7782 |
| 10 | 33930 |
| 11 | 172430 |
| 12 | 1106754 |
| 13 | 6432236 |
| 14 | 45188572 |
| 15 | 372437930 |
| 16 | 2728674526 |
| 17 | 23648822368 |
| 18 | 233010291526 |
| 19 | 2083328647344 |
[1,2,6,8,24,126,316,1344,7782,33930,172430, 1106754,6432236,45188572,372437930,2728674526, 23648822368,233010291526,2083328647344] |