The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 6 |
| 5 | 19 |
| 6 | 49 |
| 7 | 163 |
| 8 | 472 |
| 9 | 1626 |
| 10 | 5034 |
| 11 | 17769 |
| 12 | 57474 |
| 13 | 206487 |
| 14 | 688881 |
| 15 | 2508195 |
| 16 | 8563020 |
| 17 | 31504240 |
| 18 | 109492960 |
| 19 | 406214878 |
| 20 | 1432030036 |
| 21 | 5349255726 |
| 22 | 19077934506 |
| 23 | 71672186953 |
| 24 | 258095737156 |
| 25 | 974311431094 |
| 26 | 3537275250214 |
| 27 | 13408623649893 |
[1,1,1,3,6,19,49,163,472,1626,5034,17769,57474, 206487,688881,2508195,8563020,31504240,109492960, 406214878,1432030036,5349255726,19077934506, 71672186953,258095737156,974311431094, 3537275250214,13408623649893] |