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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 0 |
| 4 | -4 |
| 5 | 64 |
| 6 | -240 |
| 7 | -2656 |
| 8 | 15360 |
| 9 | -88064 |
| 10 | -1714176 |
| 11 | -28506112 |
| 12 | 59061248 |
| 13 | 1975595008 |
| 14 | -107448238080 |
| 15 | 858018086912 |
| 16 | 12209125720064 |
| 17 | 61138306793472 |
| 18 | -297002777247744 |
| 19 | -7586668200067072 |
| 20 | 309144292445913088 |
[1,1,0,-4,64,-240,-2656,15360,-88064,-1714176, -28506112,59061248,1975595008,-107448238080, 858018086912,12209125720064,61138306793472, -297002777247744,-7586668200067072, 309144292445913088] |