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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 9 |
| 3 | 120 |
| 4 | 1925 |
| 5 | 34398 |
| 6 | 659736 |
| 7 | 13302432 |
| 8 | 278397405 |
| 9 | 5996669250 |
| 10 | 132166590270 |
| 11 | 2967978162240 |
| 12 | 67694635250424 |
| 13 | 1564409223571600 |
| 14 | 36561597688116000 |
| 15 | 862822254602816640 |
| 16 | 20535537339485077005 |
| 17 | 492426552811873991850 |
| 18 | 11886753074132473787250 |
| 19 | 288645723487776840570000 |
[1,9,120,1925,34398,659736,13302432,278397405, 5996669250,132166590270,2967978162240, 67694635250424,1564409223571600,36561597688116000, 862822254602816640,20535537339485077005, 492426552811873991850,11886753074132473787250, 288645723487776840570000] |