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| n | a(n) |
|---|---|
| 6 | 28 |
| 7 | 4240 |
| 8 | 344320 |
| 9 | 23872320 |
| 10 | 1603840000 |
| 11 | 109616815616 |
| 12 | 7785535242240 |
| 13 | 580217967114240 |
| 14 | 45559682696478700 |
| 15 | 3774254616000000000 |
| 16 | 329816052160897000000 |
| 17 | 30372942170151000000000 |
| 18 | 2943608844201080000000000 |
[28,4240,344320,23872320,1603840000,109616815616, 7785535242240,580217967114240,45559682696478700, 3774254616000000000,329816052160897000000, 30372942170151000000000,2943608844201080000000000] |