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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 5 |
| 3 | 20 |
| 4 | 117 |
| 5 | 1024 |
| 6 | 13357 |
| 7 | 259920 |
| 8 | 7539421 |
| 9 | 326177280 |
| 10 | 21040987113 |
| 11 | 2024032315968 |
| 12 | 290333133984905 |
| 13 | 62102074862600192 |
| 14 | 19808204598680574457 |
| 15 | 9421371079480456587520 |
| 16 | 6682097668647718038428569 |
| 17 | 7067102111711681259234263040 |
| 18 | 11145503882824383823706372042925 |
[1,2,5,20,117,1024,13357,259920,7539421,326177280, 21040987113,2024032315968,290333133984905, 62102074862600192,19808204598680574457, 9421371079480456587520,6682097668647718038428569, 7067102111711681259234263040, 11145503882824383823706372042925] |