The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 10 |
| 3 | 52 |
| 4 | 278 |
| 5 | 1508 |
| 6 | 8262 |
| 7 | 45604 |
| 8 | 253186 |
| 9 | 1412196 |
| 10 | 7906866 |
| 11 | 44411420 |
| 12 | 250124308 |
| 13 | 1411963200 |
| 14 | 7986664250 |
| 15 | 45255888828 |
| 16 | 256840959728 |
| 17 | 1459686175768 |
| 18 | 8306130772008 |
| 19 | 47318321533008 |
| 20 | 269839722667800 |
| 21 | 1540242835509060 |
| 22 | 8799238591245006 |
| 23 | 50308756959106988 |
[1,2,10,52,278,1508,8262,45604,253186,1412196, 7906866,44411420,250124308,1411963200,7986664250, 45255888828,256840959728,1459686175768, 8306130772008,47318321533008,269839722667800, 1540242835509060,8799238591245006, 50308756959106988] |