The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | -2 |
| 5 | 5 |
| 6 | 6 |
| 7 | 131 |
| 8 | -552 |
| 9 | 3065 |
| 10 | -10934 |
| 11 | 216511 |
| 12 | -1516052 |
| 13 | 13359125 |
| 14 | -110965074 |
| 15 | 1704426491 |
| 16 | -17363056752 |
| 17 | 210045171185 |
| 18 | -2585510594414 |
| 19 | 41595973502071 |
| 20 | -563643499480652 |
| 21 | 8626434032607245 |
| 22 | -136389526384050954 |
[0,1,1,1,-2,5,6,131,-552,3065,-10934,216511, -1516052,13359125,-110965074,1704426491, -17363056752,210045171185,-2585510594414, 41595973502071,-563643499480652,8626434032607245, -136389526384050954] |