The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 3 |
| 5 | 7 |
| 6 | 15 |
| 7 | 31 |
| 8 | 73 |
| 9 | 307 |
| 10 | 1451 |
| 11 | 6775 |
| 12 | 33773 |
| 13 | 192865 |
| 14 | 1471507 |
| 15 | 13382667 |
| 16 | 137085697 |
| 17 | 1565839497 |
| 18 | 20450552451 |
| 19 | 319414253795 |
| 20 | 5882181538191 |
| 21 | 126047394686961 |
| 22 | 3114606848932875 |
[1,1,1,3,7,15,31,73,307,1451,6775,33773,192865, 1471507,13382667,137085697,1565839497,20450552451, 319414253795,5882181538191,126047394686961, 3114606848932875] |