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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 60 |
| 4 | 2496 |
| 5 | 276240 |
| 6 | 83893248 |
| 7 | 72508524480 |
| 8 | 182341191057408 |
| 9 | 1348995112077074688 |
| 10 | 29528107099434111467520 |
| 11 | 1918583757808453356238126080 |
| 12 | 370812729559366641806998574727168 |
[1,4,60,2496,276240,83893248,72508524480, 182341191057408,1348995112077074688, 29528107099434111467520, 1918583757808453356238126080, 370812729559366641806998574727168] |