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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 54 |
| 4 | 768 |
| 5 | 75000 |
| 6 | 233280 |
| 7 | 592950960 |
| 8 | 5284823040 |
| 9 | 1735643790720 |
| 10 | 5670000000000 |
| 11 | 1035338990313196800 |
| 12 | 17163493362892800 |
| 13 | 145077660657859734604800 |
| 14 | 9653278129532887449600 |
[1,4,54,768,75000,233280,592950960,5284823040, 1735643790720,5670000000000,1035338990313196800, 17163493362892800,145077660657859734604800, 9653278129532887449600] |