The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | -1 |
| 2 | 2 |
| 3 | 4 |
| 4 | -56 |
| 5 | 80 |
| 6 | -352 |
| 7 | 64 |
| 8 | 2176 |
| 9 | -4864 |
| 10 | 31232 |
| 11 | -23552 |
| 12 | -14336 |
| 13 | 217088 |
| 14 | -2056192 |
| 15 | 2375680 |
| 16 | -7307264 |
| 17 | -4390912 |
| 18 | 102367232 |
| 19 | -169607168 |
| 20 | 877133824 |
| 21 | -397410304 |
| 22 | -3042967552 |
| 23 | 9265217536 |
| 24 | -68308434944 |
| 25 | 62495129600 |
| 26 | -78483816448 |
| 27 | -342993403904 |
[-1,2,4,-56,80,-352,64,2176,-4864,31232,-23552, -14336,217088,-2056192,2375680,-7307264,-4390912, 102367232,-169607168,877133824,-397410304, -3042967552,9265217536,-68308434944,62495129600, -78483816448,-342993403904] |