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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 6 |
| 3 | 60 |
| 4 | 696 |
| 5 | 9120 |
| 6 | 134640 |
| 7 | 2227680 |
| 8 | 41005440 |
| 9 | 833172480 |
| 10 | 18546796800 |
| 11 | 449223667200 |
| 12 | 11766674304000 |
| 13 | 331501679308800 |
| 14 | 9997170543360000 |
| 15 | 321355745238528000 |
| 16 | 10969253822951424000 |
| 17 | 396269940892041216000 |
[1,6,60,696,9120,134640,2227680,41005440, 833172480,18546796800,449223667200,11766674304000, 331501679308800,9997170543360000, 321355745238528000,10969253822951424000, 396269940892041216000] |