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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 28 |
| 2 | 532 |
| 3 | 8560 |
| 4 | 125776 |
| 5 | 1747648 |
| 6 | 23401792 |
| 7 | 305401600 |
| 8 | 3912299776 |
| 9 | 49432480768 |
| 10 | 618099069952 |
| 11 | 7666644643840 |
| 12 | 94496470552576 |
| 13 | 1158938055589888 |
| 14 | 14157139120832512 |
| 15 | 172384964172513280 |
[1,28,532,8560,125776,1747648,23401792,305401600, 3912299776,49432480768,618099069952,7666644643840, 94496470552576,1158938055589888,14157139120832512, 172384964172513280] |