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| n | a(n) |
|---|---|
| 2 | 1 |
| 3 | 2 |
| 4 | 8 |
| 5 | 68 |
| 6 | 952 |
| 7 | 19312 |
| 8 | 533544 |
| 9 | 19209584 |
| 10 | 873274112 |
| 11 | 48904686848 |
| 12 | 3307732742656 |
| 13 | 265835173240320 |
| 14 | 25041294346380800 |
| 15 | 2732759857218994176 |
| 16 | 342041866136488863232 |
| 17 | 48672372916773453011968 |
| 18 | 7813786873387535522529280 |
| 19 | 1405550552561695118460387328 |
[1,2,8,68,952,19312,533544,19209584,873274112, 48904686848,3307732742656,265835173240320, 25041294346380800,2732759857218994176, 342041866136488863232,48672372916773453011968, 7813786873387535522529280, 1405550552561695118460387328] |