The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 2 |
| 4 | 14 |
| 5 | 88 |
| 6 | 598 |
| 7 | 4496 |
| 8 | 37550 |
| 9 | 347008 |
| 10 | 3527758 |
| 11 | 39209216 |
| 12 | 473596070 |
| 13 | 6182284288 |
| 14 | 86779569238 |
| 15 | 1303866853376 |
| 16 | 20884006863710 |
| 17 | 355267697410048 |
| 18 | 6397563946377118 |
| 19 | 121586922638606336 |
| 20 | 2432161265800164950 |
| 21 | 51081039175603191808 |
| 22 | 1123862030028821404198 |
[0,0,0,2,14,88,598,4496,37550,347008,3527758, 39209216,473596070,6182284288,86779569238, 1303866853376,20884006863710,355267697410048, 6397563946377118,121586922638606336, 2432161265800164950,51081039175603191808, 1123862030028821404198] |