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| n | a(n) |
|---|---|
| 1 | -1 |
| 2 | 1 |
| 3 | 4 |
| 4 | 14 |
| 5 | 16 |
| 6 | -400 |
| 7 | -5312 |
| 8 | -33040 |
| 9 | 134400 |
| 10 | 7141632 |
| 11 | 104530944 |
| 12 | 438163968 |
| 13 | -19703033856 |
| 14 | -615381651456 |
| 15 | -8122606469120 |
| 16 | 54420468856832 |
| 17 | 5822016615940096 |
| 18 | 150504948558528512 |
| 19 | 1126972987747336192 |
| 20 | -72753308251479212032 |
[-1,1,4,14,16,-400,-5312,-33040,134400,7141632, 104530944,438163968,-19703033856,-615381651456, -8122606469120,54420468856832,5822016615940096, 150504948558528512,1126972987747336192, -72753308251479212032] |