The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | -1 |
| 3 | 3 |
| 4 | -7 |
| 5 | 28 |
| 6 | -79 |
| 7 | 350 |
| 8 | -1075 |
| 9 | 5020 |
| 10 | -16180 |
| 11 | 78023 |
| 12 | -259417 |
| 13 | 1278340 |
| 14 | -4343642 |
| 15 | 21740636 |
| 16 | -75065787 |
| 17 | 380161308 |
| 18 | -1328887420 |
| 19 | 6792111260 |
| 20 | -23975385148 |
| 21 | 123448657904 |
| 22 | -439228736887 |
| 23 | 2275311657814 |
| 24 | -8148868193557 |
| 25 | 42427160829508 |
| 26 | -152792221834364 |
[1,1,-1,3,-7,28,-79,350,-1075,5020,-16180,78023, -259417,1278340,-4343642,21740636,-75065787, 380161308,-1328887420,6792111260,-23975385148, 123448657904,-439228736887,2275311657814, -8148868193557,42427160829508,-152792221834364] |