The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 25 |
| 5 | 130 |
| 6 | 810 |
| 7 | 5881 |
| 8 | 48806 |
| 9 | 455706 |
| 10 | 4727881 |
| 11 | 53955682 |
| 12 | 671730246 |
| 13 | 9059714665 |
| 14 | 131588822822 |
| 15 | 2047796305470 |
| 16 | 33992509701721 |
| 17 | 599526848094850 |
| 18 | 11195864285933682 |
| 19 | 220692569175568729 |
| 20 | 4579248276057441926 |
| 21 | 99767702172338210898 |
| 22 | 2277136869014579978473 |
| 23 | 54336724559407913237122 |
[1,1,2,6,25,130,810,5881,48806,455706,4727881, 53955682,671730246,9059714665,131588822822, 2047796305470,33992509701721,599526848094850, 11195864285933682,220692569175568729, 4579248276057441926,99767702172338210898, 2277136869014579978473,54336724559407913237122] |