| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 2 |
| 2 | -1 |
| 3 | -16 |
| 4 | 42 |
| 5 | 500 |
| 6 | -3210 |
| 7 | -31960 |
| 8 | 409640 |
| 9 | 3197360 |
| 10 | -78190200 |
| 11 | -405352000 |
| 12 | 20714298000 |
| 13 | 39783504800 |
| 14 | -7213870190800 |
| 15 | 15836666456000 |
| 16 | 3165414330000000 |
| 17 | -23690623723936000 |
| 18 | -1688397526908144000 |
[0,2,-1,-16,42,500,-3210,-31960,409640,3197360, -78190200,-405352000,20714298000,39783504800, -7213870190800,15836666456000,3165414330000000, -23690623723936000,-1688397526908144000] |