The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | -1 |
| 4 | 5 |
| 5 | -19 |
| 6 | 67 |
| 7 | -232 |
| 8 | 804 |
| 9 | -2806 |
| 10 | 9878 |
| 11 | -35072 |
| 12 | 125512 |
| 13 | -452388 |
| 14 | 1641028 |
| 15 | -5986993 |
| 16 | 21954973 |
| 17 | -80884423 |
| 18 | 299233543 |
| 19 | -1111219333 |
| 20 | 4140813373 |
| 21 | -15478839553 |
| 22 | 58028869153 |
| 23 | -218123355523 |
| 24 | 821908275547 |
| 25 | -3104046382351 |
| 26 | 11747506651599 |
| 27 | -44546351423299 |
| 28 | 169227201341651 |
[1,0,0,-1,5,-19,67,-232,804,-2806,9878,-35072, 125512,-452388,1641028,-5986993,21954973, -80884423,299233543,-1111219333,4140813373, -15478839553,58028869153,-218123355523, 821908275547,-3104046382351,11747506651599, -44546351423299,169227201341651] |