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 | 25 |
| 5 | 73 |
| 6 | 285 |
| 7 | 955 |
| 8 | 3919 |
| 9 | 14305 |
| 10 | 60725 |
| 11 | 234803 |
| 12 | 1021695 |
| 13 | 4117745 |
| 14 | 18255063 |
| 15 | 75905883 |
| 16 | 341433697 |
| 17 | 1454584649 |
| 18 | 6619281441 |
| 19 | 28750556287 |
| 20 | 132079753073 |
| 21 | 582781728613 |
| 22 | 2698485000981 |
| 23 | 12062618604059 |
| 24 | 56226922073633 |
| 25 | 254100802569969 |
| 26 | 1191175614141125 |
| 27 | 5433263784163247 |
| 28 | 25595283861452437 |
[1,1,3,7,25,73,285,955,3919,14305,60725,234803, 1021695,4117745,18255063,75905883,341433697, 1454584649,6619281441,28750556287,132079753073, 582781728613,2698485000981,12062618604059, 56226922073633,254100802569969,1191175614141125, 5433263784163247,25595283861452437] |