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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 144000 |
| 3 | 455282248974336000000 |
| 4 | 9608917807566747651759509633033255126040576000000000000 |
[1,3,144000,455282248974336000000, 96089178075667476517595096330332551260405760000000\ 00000] |