The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | -2 |
| 3 | -6 |
| 4 | -12 |
| 5 | 0 |
| 6 | 240 |
| 7 | 2520 |
| 8 | 21840 |
| 9 | 181440 |
| 10 | 1481760 |
| 11 | 11642400 |
| 12 | 80498880 |
| 13 | 311351040 |
| 14 | -4739454720 |
| 15 | -183437654400 |
| 16 | -4300276780800 |
| 17 | -88851284121600 |
| 18 | -1754954007206400 |
| 19 | -34107089784768000 |
| 20 | -659574028252339200 |
| 21 | -12724865943229440000 |
| 22 | -244046146272658329600 |
[1,0,-2,-6,-12,0,240,2520,21840,181440,1481760, 11642400,80498880,311351040,-4739454720, -183437654400,-4300276780800,-88851284121600, -1754954007206400,-34107089784768000, -659574028252339200,-12724865943229440000, -244046146272658329600] |