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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 12 |
| 4 | 52 |
| 5 | 1992 |
| 6 | 43472 |
| 7 | 8084672 |
| 8 | 785972800 |
| 9 | 632010796352 |
| 10 | 260819509251776 |
| 11 | 879345967412550400 |
| 12 | 1508148706710022883840 |
| 13 | 20993821611583601278837888 |
| 14 | 147923394778079541856196475392 |
| 15 | 8426633557858801012990635249817088 |
[1,2,12,52,1992,43472,8084672,785972800, 632010796352,260819509251776,879345967412550400, 1508148706710022883840,20993821611583601278837888, 147923394778079541856196475392, 8426633557858801012990635249817088] |