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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 12 |
| 3 | 2160 |
| 4 | 2449440000 |
| 5 | 8488905214204800000000000 |
| 6 | 3025568387202006082882734693673523654400000000000000000000000000 |
[1,2,12,2160,2449440000,8488905214204800000000000, 30255683872020060828827346936735236544000000000000\ 00000000000000] |