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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 12 |
| 4 | 240 |
| 5 | 18480 |
| 6 | 6708240 |
| 7 | 14088352320 |
| 8 | 203200845886080 |
| 9 | 23190071108511726720 |
| 10 | 23647206583059346913915520 |
| 11 | 239883631139512760372860490507520 |
[1,1,2,12,240,18480,6708240,14088352320, 203200845886080,23190071108511726720, 23647206583059346913915520, 239883631139512760372860490507520] |