The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | -1 |
| 2 | 2 |
| 3 | -3 |
| 4 | 0 |
| 5 | 30 |
| 6 | -240 |
| 7 | 1470 |
| 8 | -6720 |
| 9 | 12600 |
| 10 | 214200 |
| 11 | -4019400 |
| 12 | 45460800 |
| 13 | -378378000 |
| 14 | 1727926200 |
| 15 | 16358542200 |
| 16 | -608230022400 |
| 17 | 10777315348800 |
| 18 | -137136749349600 |
| 19 | 1088994283977600 |
| 20 | 4431653341315200 |
| 21 | -412892994284971200 |
| 22 | 10654104643073892000 |
| 23 | -189834731018203471200 |
[1,-1,2,-3,0,30,-240,1470,-6720,12600,214200, -4019400,45460800,-378378000,1727926200, 16358542200,-608230022400,10777315348800, -137136749349600,1088994283977600, 4431653341315200,-412892994284971200, 10654104643073892000,-189834731018203471200] |