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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 6 |
| 2 | 140 |
| 3 | 4620 |
| 4 | 180180 |
| 5 | 7759752 |
| 6 | 356948592 |
| 7 | 17210021400 |
| 8 | 859544957700 |
| 9 | 44123307828600 |
| 10 | 2315270298060720 |
| 11 | 123691561681243920 |
| 12 | 6707888537328997200 |
| 13 | 368417878127146461600 |
| 14 | 20455964090297751153600 |
| 15 | 1146556787261188952159280 |
| 16 | 64797319609481605046295780 |
[1,6,140,4620,180180,7759752,356948592, 17210021400,859544957700,44123307828600, 2315270298060720,123691561681243920, 6707888537328997200,368417878127146461600, 20455964090297751153600,1146556787261188952159280, 64797319609481605046295780] |