The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 7 |
| 4 | 28 |
| 5 | 81 |
| 6 | 352 |
| 7 | 1154 |
| 8 | 5208 |
| 9 | 18450 |
| 10 | 85202 |
| 11 | 317719 |
| 12 | 1489930 |
| 13 | 5762701 |
| 14 | 27316040 |
| 15 | 108584686 |
| 16 | 518762827 |
| 17 | 2106471761 |
| 18 | 10123531026 |
| 19 | 41810856886 |
| 20 | 201869469476 |
| 21 | 845355773410 |
| 22 | 4096563483555 |
| 23 | 17353296616714 |
| 24 | 84345572763846 |
| 25 | 360774559654579 |
| 26 | 1757889969930777 |
| 27 | 7581645820626841 |
| 28 | 37018777212600691 |
[1,1,3,7,28,81,352,1154,5208,18450,85202,317719, 1489930,5762701,27316040,108584686,518762827, 2106471761,10123531026,41810856886,201869469476, 845355773410,4096563483555,17353296616714, 84345572763846,360774559654579,1757889969930777, 7581645820626841,37018777212600691] |