| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 2 |
| 3 | 2 |
| 4 | -8 |
| 5 | -44 |
| 6 | 8 |
| 7 | 944 |
| 8 | 2304 |
| 9 | -27632 |
| 10 | -183776 |
| 11 | 975072 |
| 12 | 15141248 |
| 13 | -27882048 |
| 14 | -1461427328 |
| 15 | -1986004224 |
| 16 | 166452797440 |
| 17 | 850359527680 |
| 18 | -21941424508416 |
| 19 | -222801125934592 |
| 20 | 3231615038191616 |
| 21 | 57863671042155520 |
[0,1,2,2,-8,-44,8,944,2304,-27632,-183776,975072, 15141248,-27882048,-1461427328,-1986004224, 166452797440,850359527680,-21941424508416, -222801125934592,3231615038191616, 57863671042155520] |