The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | -6 |
| 3 | 36 |
| 4 | -216 |
| 5 | 1404 |
| 6 | -9648 |
| 7 | 68904 |
| 8 | -506304 |
| 9 | 3802464 |
| 10 | -29055024 |
| 11 | 225142416 |
| 12 | -1764900576 |
| 13 | 13970400480 |
| 14 | -111506362560 |
| 15 | 896391836928 |
| 16 | -7251109424640 |
| 17 | 58978357310592 |
| 18 | -482049643011840 |
| 19 | 3957079727715840 |
| 20 | -32609916223598592 |
| 21 | 269682253882186752 |
[1,3,-6,36,-216,1404,-9648,68904,-506304,3802464, -29055024,225142416,-1764900576,13970400480, -111506362560,896391836928,-7251109424640, 58978357310592,-482049643011840,3957079727715840, -32609916223598592,269682253882186752] |