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 | 71 |
| 6 | 249 |
| 7 | 847 |
| 8 | 3029 |
| 9 | 10683 |
| 10 | 39689 |
| 11 | 147239 |
| 12 | 551221 |
| 13 | 2092331 |
| 14 | 8054273 |
| 15 | 31025487 |
| 16 | 120541229 |
| 17 | 472911683 |
| 18 | 1862132473 |
| 19 | 7357610135 |
| 20 | 29280001861 |
| 21 | 117020171467 |
| 22 | 468756101073 |
| 23 | 1886067433695 |
| 24 | 7620751816541 |
| 25 | 30858228939091 |
| 26 | 125300855281193 |
| 27 | 510567657915239 |
| 28 | 2085135808856565 |
[1,1,3,7,25,71,249,847,3029,10683,39689,147239, 551221,2092331,8054273,31025487,120541229, 472911683,1862132473,7357610135,29280001861, 117020171467,468756101073,1886067433695, 7620751816541,30858228939091,125300855281193, 510567657915239,2085135808856565] |