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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 24 |
| 2 | 420 |
| 3 | 6720 |
| 4 | 105840 |
| 5 | 1693440 |
| 6 | 27941760 |
| 7 | 479001600 |
| 8 | 8562153600 |
| 9 | 159826867200 |
| 10 | 3116623910400 |
| 11 | 63465795993600 |
| 12 | 1348648164864000 |
| 13 | 29877743960064000 |
| 14 | 689322235650048000 |
| 15 | 16543733655601152000 |
| 16 | 412559358036553728000 |
| 17 | 10678006913887272960000 |
| 18 | 286526518855975157760000 |
[1,24,420,6720,105840,1693440,27941760,479001600, 8562153600,159826867200,3116623910400, 63465795993600,1348648164864000,29877743960064000, 689322235650048000,16543733655601152000, 412559358036553728000,10678006913887272960000, 286526518855975157760000] |