The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 2 |
| 4 | 4 |
| 5 | 12 |
| 6 | 128 |
| 7 | 464 |
| 8 | 1296 |
| 9 | 336 |
| 10 | 85600 |
| 11 | 838752 |
| 12 | 4372160 |
| 13 | -11036608 |
| 14 | 148860416 |
| 15 | 5128035072 |
| 16 | 54261590272 |
| 17 | -109537337088 |
| 18 | -1474575037952 |
| 19 | 68456854604288 |
| 20 | 1579094994228224 |
| 21 | 1239349299477504 |
| 22 | -145025202842173440 |
[1,1,2,2,4,12,128,464,1296,336,85600,838752, 4372160,-11036608,148860416,5128035072, 54261590272,-109537337088,-1474575037952, 68456854604288,1579094994228224,1239349299477504, -145025202842173440] |