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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 20 |
| 4 | 504 |
| 5 | 23968 |
| 6 | 1851520 |
| 7 | 211575936 |
| 8 | 33566973440 |
| 9 | 7062343608320 |
| 10 | 1903365244784640 |
| 11 | 639521861269258240 |
| 12 | 262112584945787699200 |
| 13 | 128722417690687207833600 |
| 14 | 74622047155540651999232000 |
| 15 | 50422787106606997974155264000 |
| 16 | 39283625022760603948312795545600 |
| 17 | 34956170646455883939814603698995200 |
| 18 | 35235028408984566235493250881290240000 |
| 19 | 39938723513704723231184585043746173747200 |
[1,2,20,504,23968,1851520,211575936,33566973440, 7062343608320,1903365244784640,639521861269258240, 262112584945787699200,128722417690687207833600, 74622047155540651999232000, 50422787106606997974155264000, 39283625022760603948312795545600, 34956170646455883939814603698995200, 35235028408984566235493250881290240000, 39938723513704723231184585043746173747200] |