The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 0 |
| 3 | 3 |
| 4 | 11 |
| 5 | 40 |
| 6 | 184 |
| 7 | 1036 |
| 8 | 12949 |
| 9 | 88488 |
| 10 | 807008 |
| 11 | 7362586 |
| 12 | 113572183 |
| 13 | 1238477032 |
| 14 | 15630890560 |
| 15 | 228998728050 |
| 16 | 4141605806441 |
| 17 | 62222251093216 |
| 18 | 1030119451142656 |
| 19 | 19050688698470434 |
| 20 | 412037845709792107 |
| 21 | 8102391640556570616 |
| 22 | 165794307361686866432 |
[1,1,0,3,11,40,184,1036,12949,88488,807008, 7362586,113572183,1238477032,15630890560, 228998728050,4141605806441,62222251093216, 1030119451142656,19050688698470434, 412037845709792107,8102391640556570616, 165794307361686866432] |