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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 320 |
| 4 | 2027520 |
| 5 | 3855986196480 |
| 6 | 8359491805553413324800 |
| 7 | 79457890145647634305213865656320000 |
| 8 | 12897878211365028383150895090566532213003150950400000 |
| 9 | 140613650417826346093374124598539442743630963394643403845144815232614400000 |
[1,4,320,2027520,3855986196480, 8359491805553413324800, 79457890145647634305213865656320000, 12897878211365028383150895090566532213003150950400\ 000, 14061365041782634609337412459853944274363096339464\ 3403845144815232614400000] |