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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | -1 |
| 3 | 2 |
| 4 | -6 |
| 5 | 16 |
| 6 | 0 |
| 7 | -624 |
| 8 | 9072 |
| 9 | -108632 |
| 10 | 1259640 |
| 11 | -14799544 |
| 12 | 179091264 |
| 13 | -2245354968 |
| 14 | 29201086824 |
| 15 | -393393411904 |
| 16 | 5472839893440 |
| 17 | -78247740884864 |
| 18 | 1141773898925952 |
| 19 | -16826235923665152 |
| 20 | 246149512349702400 |
[0,1,-1,2,-6,16,0,-624,9072,-108632,1259640, -14799544,179091264,-2245354968,29201086824, -393393411904,5472839893440,-78247740884864, 1141773898925952,-16826235923665152, 246149512349702400] |