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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3432 |
| 3 | 399072960 |
| 4 | 472518347558400 |
| 5 | 102038786510159790720 |
| 6 | 9792481437399343532438160 |
[1,1,3432,399072960,472518347558400, 102038786510159790720,9792481437399343532438160] |