The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 8 |
| 5 | 44 |
| 6 | 302 |
| 7 | 2512 |
| 8 | 24558 |
| 9 | 275676 |
| 10 | 3493862 |
| 11 | 49339784 |
| 12 | 768182846 |
| 13 | 13071470788 |
| 14 | 241332513606 |
| 15 | 4804601266896 |
| 16 | 102599581877918 |
| 17 | 2339270285673068 |
| 18 | 56716397892998246 |
| 19 | 1457071974028941400 |
| 20 | 39538338850995279294 |
| 21 | 1130018112921128323668 |
| 22 | 33928819073838398622662 |
[1,1,1,2,8,44,302,2512,24558,275676,3493862, 49339784,768182846,13071470788,241332513606, 4804601266896,102599581877918,2339270285673068, 56716397892998246,1457071974028941400, 39538338850995279294,1130018112921128323668, 33928819073838398622662] |