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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 96 |
| 5 | 480 |
| 6 | 17280 |
| 7 | 120960 |
| 8 | 30965760 |
| 9 | 2508226560 |
| 10 | 250822656000 |
| 11 | 2759049216000 |
| 12 | 9535274090496000 |
| 13 | 123958563176448000 |
| 14 | 24295878382583808000 |
| 15 | 5466572636081356800000 |
| 16 | 179128652139113899622400000 |
| 17 | 3045187086364936293580800000 |
| 18 | 53278593263040925392489676800000 |
[1,1,2,6,96,480,17280,120960,30965760,2508226560, 250822656000,2759049216000,9535274090496000, 123958563176448000,24295878382583808000, 5466572636081356800000, 179128652139113899622400000, 3045187086364936293580800000, 53278593263040925392489676800000] |