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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | -1 |
| 2 | -2 |
| 3 | 2 |
| 4 | 16 |
| 5 | -40 |
| 6 | -320 |
| 7 | 1040 |
| 8 | 12160 |
| 9 | -52480 |
| 10 | -742400 |
| 11 | 3872000 |
| 12 | 66457600 |
| 13 | -411136000 |
| 14 | -8202444800 |
| 15 | 58479872000 |
| 16 | 1335009280000 |
| 17 | -10791497728000 |
| 18 | -277035646976000 |
| 19 | 2502527565824000 |
| 20 | 71391934873600000 |
| 21 | -712816377856000000 |
| 22 | -22367684235100160000 |
| 23 | 244597236078018560000 |
[1,-1,-2,2,16,-40,-320,1040,12160,-52480,-742400, 3872000,66457600,-411136000,-8202444800, 58479872000,1335009280000,-10791497728000, -277035646976000,2502527565824000, 71391934873600000,-712816377856000000, -22367684235100160000,244597236078018560000] |