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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | -1 |
| 3 | 4 |
| 4 | -8 |
| 5 | 20 |
| 6 | -61 |
| 7 | 208 |
| 8 | -888 |
| 9 | 4304 |
| 10 | -24001 |
| 11 | 149312 |
| 12 | -1028048 |
| 13 | 7745088 |
| 14 | -63374221 |
| 15 | 559452416 |
| 16 | -5299033488 |
| 17 | 53597321472 |
| 18 | -576514338721 |
| 19 | 6570832389120 |
| 20 | -79100066353208 |
| 21 | 1002840464045056 |
| 22 | -13355627237749501 |
| 23 | 186406420596609024 |
[0,1,-1,4,-8,20,-61,208,-888,4304,-24001,149312, -1028048,7745088,-63374221,559452416,-5299033488, 53597321472,-576514338721,6570832389120, -79100066353208,1002840464045056, -13355627237749501,186406420596609024] |