The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | -1 |
| 2 | 0 |
| 3 | 2 |
| 4 | -8 |
| 5 | 24 |
| 6 | -56 |
| 7 | 104 |
| 8 | 64 |
| 9 | -1792 |
| 10 | 12672 |
| 11 | -68608 |
| 12 | 309376 |
| 13 | -1203840 |
| 14 | 2917888 |
| 15 | 5570816 |
| 16 | -163782656 |
| 17 | 1636425728 |
| 18 | -12716052480 |
| 19 | 86205304832 |
| 20 | -495644917760 |
| 21 | 2289265803264 |
| 22 | -4004259037184 |
| 23 | -73881736609792 |
| 24 | 1359174582304768 |
[1,-1,0,2,-8,24,-56,104,64,-1792,12672,-68608, 309376,-1203840,2917888,5570816,-163782656, 1636425728,-12716052480,86205304832,-495644917760, 2289265803264,-4004259037184,-73881736609792, 1359174582304768] |