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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 6 |
| 2 | 120 |
| 3 | 19399380 |
| 4 | 195534950863140268380 |
| 5 | 538938984694949877040715541221415046162838700 |
| 6 | 216487559804430601784907786655491617909711008142914104790481010259258659171900 |
[1,6,120,19399380,195534950863140268380, 538938984694949877040715541221415046162838700, 21648755980443060178490778665549161790971100814291\ 4104790481010259258659171900] |