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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 16 |
| 2 | 120 |
| 3 | 832 |
| 4 | 5696 |
| 5 | 38912 |
| 6 | 265728 |
| 7 | 1814528 |
| 8 | 12390400 |
| 9 | 84606976 |
| 10 | 577732608 |
| 11 | 3945005056 |
| 12 | 26938179584 |
| 13 | 183945396224 |
| 14 | 1256057733120 |
| 15 | 8576898695168 |
| 16 | 58566727696384 |
| 17 | 399918632009728 |
| 18 | 2730815234506752 |
| 19 | 18647172819976192 |
[1,16,120,832,5696,38912,265728,1814528,12390400, 84606976,577732608,3945005056,26938179584, 183945396224,1256057733120,8576898695168, 58566727696384,399918632009728,2730815234506752, 18647172819976192] |