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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 1134 |
| 4 | 333132800 |
| 5 | 1319947441510156250 |
| 6 | 876533819183888230348458418944000 |
| 7 | 1185269534290897564185384010731432113450477770983533184 |
[1,1,4,1134,333132800,1319947441510156250, 876533819183888230348458418944000, 11852695342908975641853840107314321134504777709835\ 33184] |