The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 3 |
| 3 | 12 |
| 4 | 114 |
| 5 | 1404 |
| 6 | 22968 |
| 7 | 456408 |
| 8 | 10762992 |
| 9 | 292851648 |
| 10 | 9038285280 |
| 11 | 311858347968 |
| 12 | 11896746473088 |
| 13 | 497156854363776 |
| 14 | 22586083785232128 |
| 15 | 1108320770197398528 |
| 16 | 58420751739908940288 |
| 17 | 3292054745517600648192 |
| 18 | 197491129333671926863872 |
| 19 | 12566253138627465234487296 |
[0,1,3,12,114,1404,22968,456408,10762992, 292851648,9038285280,311858347968,11896746473088, 497156854363776,22586083785232128, 1108320770197398528,58420751739908940288, 3292054745517600648192,197491129333671926863872, 12566253138627465234487296] |