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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 44 |
| 4 | 716 |
| 5 | 24416 |
| 6 | 1680224 |
| 7 | 229468288 |
| 8 | 61820527104 |
| 9 | 32848197477760 |
| 10 | 34502874046006912 |
| 11 | 71850629135663531776 |
| 12 | 297429744309497638961920 |
| 13 | 2452504520881914016303901696 |
| 14 | 40340635076928240671195746599936 |
| 15 | 1324981038432182976845483456362661888 |
| 16 | 86953044949519288083916385603832568137728 |
[1,2,6,44,716,24416,1680224,229468288,61820527104, 32848197477760,34502874046006912, 71850629135663531776,297429744309497638961920, 2452504520881914016303901696, 40340635076928240671195746599936, 1324981038432182976845483456362661888, 86953044949519288083916385603832568137728] |