The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 5 |
| 3 | 15 |
| 4 | 47 |
| 5 | 158 |
| 6 | 551 |
| 7 | 1978 |
| 8 | 7280 |
| 9 | 27287 |
| 10 | 103890 |
| 11 | 400726 |
| 12 | 1562935 |
| 13 | 6152911 |
| 14 | 24424119 |
| 15 | 97651753 |
| 16 | 392890089 |
| 17 | 1589751091 |
| 18 | 6465135718 |
| 19 | 26411296607 |
| 20 | 108341410515 |
| 21 | 446089923524 |
| 22 | 1843009043745 |
| 23 | 7638272615102 |
| 24 | 31747762868828 |
| 25 | 132306896027373 |
| 26 | 552742459514066 |
| 27 | 2314493115874922 |
| 28 | 9712068714424451 |
[1,2,5,15,47,158,551,1978,7280,27287,103890, 400726,1562935,6152911,24424119,97651753, 392890089,1589751091,6465135718,26411296607, 108341410515,446089923524,1843009043745, 7638272615102,31747762868828,132306896027373, 552742459514066,2314493115874922,9712068714424451] |