| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | -1 |
| 3 | 1 |
| 4 | -8 |
| 5 | 45 |
| 6 | -301 |
| 7 | 2357 |
| 8 | -21608 |
| 9 | 223769 |
| 10 | -2602081 |
| 11 | 33484713 |
| 12 | -473210528 |
| 13 | 7282225093 |
| 14 | -121272163741 |
| 15 | 2172791685469 |
| 16 | -41680241726768 |
| 17 | 852337358029617 |
| 18 | -18510436676621281 |
| 19 | 425474580069715025 |
| 20 | -10319766893265298328 |
[0,1,-1,1,-8,45,-301,2357,-21608,223769,-2602081, 33484713,-473210528,7282225093,-121272163741, 2172791685469,-41680241726768,852337358029617, -18510436676621281,425474580069715025, -10319766893265298328] |