The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 4 |
| 5 | 9 |
| 6 | 20 |
| 7 | 47 |
| 8 | 112 |
| 9 | 277 |
| 10 | 692 |
| 11 | 1756 |
| 12 | 4483 |
| 13 | 11525 |
| 14 | 29688 |
| 15 | 76620 |
| 16 | 197745 |
| 17 | 510234 |
| 18 | 1315348 |
| 19 | 3387687 |
| 20 | 8715037 |
| 21 | 22395482 |
| 22 | 57487071 |
| 23 | 147411172 |
| 24 | 377624359 |
| 25 | 966473181 |
| 26 | 2471400115 |
| 27 | 6314595259 |
| 28 | 16121970455 |
| 29 | 41132128662 |
| 30 | 104870142461 |
[1,1,1,2,4,9,20,47,112,277,692,1756,4483,11525, 29688,76620,197745,510234,1315348,3387687,8715037, 22395482,57487071,147411172,377624359,966473181, 2471400115,6314595259,16121970455,41132128662, 104870142461] |