| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 20 |
| 3 | 980 |
| 4 | 232848 |
| 5 | 267227532 |
| 6 | 1478619421136 |
| 7 | 39405996318420160 |
| 8 | 5055160684040254910720 |
| 9 | 3120344782196754906063540800 |
| 10 | 9265037718181937012241727284450000 |
| 11 | 132307448895406086706107959899799334375000 |
[1,2,20,980,232848,267227532,1478619421136, 39405996318420160,5055160684040254910720, 3120344782196754906063540800, 9265037718181937012241727284450000, 132307448895406086706107959899799334375000] |