The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 9 |
| 5 | 27 |
| 6 | 87 |
| 7 | 350 |
| 8 | 1675 |
| 9 | 7848 |
| 10 | 36711 |
| 11 | 196510 |
| 12 | 1177139 |
| 13 | 6908609 |
| 14 | 40106433 |
| 15 | 256572630 |
| 16 | 1785661795 |
| 17 | 12221831460 |
| 18 | 82732094377 |
| 19 | 603846490132 |
| 20 | 4714585241090 |
| 21 | 36290179829390 |
| 22 | 276421527541533 |
[1,1,3,9,27,87,350,1675,7848,36711,196510,1177139, 6908609,40106433,256572630,1785661795,12221831460, 82732094377,603846490132,4714585241090, 36290179829390,276421527541533] |