The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 28 |
| 5 | 209 |
| 6 | 1806 |
| 7 | 18997 |
| 8 | 235544 |
| 9 | 3322881 |
| 10 | 52688890 |
| 11 | 929147141 |
| 12 | 18023207412 |
| 13 | 381330466321 |
| 14 | 8740727309510 |
| 15 | 215767934510325 |
| 16 | 5706703994412976 |
| 17 | 160994795504231297 |
| 18 | 4825786400923162482 |
| 19 | 153160894479441852037 |
| 20 | 5131078462229088189260 |
[1,2,5,28,209,1806,18997,235544,3322881,52688890, 929147141,18023207412,381330466321,8740727309510, 215767934510325,5706703994412976, 160994795504231297,4825786400923162482, 153160894479441852037,5131078462229088189260] |