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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 6 |
| 2 | 72 |
| 3 | 1080 |
| 4 | 18144 |
| 5 | 326592 |
| 6 | 6158592 |
| 7 | 120092544 |
| 8 | 2401850880 |
| 9 | 48997757952 |
| 10 | 1015589892096 |
| 11 | 21327387734016 |
| 12 | 452796847276032 |
| 13 | 9702789584486400 |
| 14 | 209580255024906240 |
| 15 | 4558370546791710720 |
| 16 | 99747873141559787520 |
| 17 | 2194453209114315325440 |
| 18 | 48508965675158549299200 |
[1,6,72,1080,18144,326592,6158592,120092544, 2401850880,48997757952,1015589892096, 21327387734016,452796847276032,9702789584486400, 209580255024906240,4558370546791710720, 99747873141559787520,2194453209114315325440, 48508965675158549299200] |