The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | -3 |
| 4 | 4 |
| 5 | 20 |
| 6 | -224 |
| 7 | 1344 |
| 8 | -5144 |
| 9 | -4320 |
| 10 | 356896 |
| 11 | -4755520 |
| 12 | 42368536 |
| 13 | -207434448 |
| 14 | -1593929336 |
| 15 | 61487349000 |
| 16 | -997231605824 |
| 17 | 9976381236224 |
| 18 | -16539522000704 |
| 19 | -1929601048449600 |
| 20 | 51992648244966016 |
| 21 | -800205465246136320 |
[1,0,1,-3,4,20,-224,1344,-5144,-4320,356896, -4755520,42368536,-207434448,-1593929336, 61487349000,-997231605824,9976381236224, -16539522000704,-1929601048449600, 51992648244966016,-800205465246136320] |