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| n | a(n) |
|---|---|
| 2 | 1 |
| 3 | 12 |
| 4 | 210 |
| 5 | 5520 |
| 6 | 206760 |
| 7 | 10473120 |
| 8 | 688821840 |
| 9 | 57039171840 |
| 10 | 5805880778880 |
| 11 | 712594633766400 |
| 12 | 103804864923513600 |
| 13 | 17709509301413529600 |
| 14 | 3498328696524626764800 |
| 15 | 792308057159314683187200 |
| 16 | 203965258080479292004608000 |
| 17 | 59229266937652347633377280000 |
| 18 | 19270409372174365076286590976000 |
[1,12,210,5520,206760,10473120,688821840, 57039171840,5805880778880,712594633766400, 103804864923513600,17709509301413529600, 3498328696524626764800,792308057159314683187200, 203965258080479292004608000, 59229266937652347633377280000, 19270409372174365076286590976000] |