| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 2 |
| 3 | 6 |
| 4 | 50 |
| 5 | 510 |
| 6 | 5882 |
| 7 | 88326 |
| 8 | 1502258 |
| 9 | 29368590 |
| 10 | 650366762 |
| 11 | 15974149686 |
| 12 | 433095937826 |
| 13 | 12829712583870 |
| 14 | 412295632858202 |
| 15 | 14292175302568806 |
| 16 | 531485147656990994 |
| 17 | 21107739762958541550 |
| 18 | 891673745283286886282 |
| 19 | 39923664347178352362006 |
[1,0,2,6,50,510,5882,88326,1502258,29368590, 650366762,15974149686,433095937826,12829712583870, 412295632858202,14292175302568806, 531485147656990994,21107739762958541550, 891673745283286886282,39923664347178352362006] |