The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 21 |
| 3 | 182 |
| 4 | 910 |
| 5 | 3255 |
| 6 | 9331 |
| 7 | 22876 |
| 8 | 49932 |
| 9 | 99645 |
| 10 | 185185 |
| 11 | 324786 |
| 12 | 542906 |
| 13 | 871507 |
| 14 | 1351455 |
| 15 | 2034040 |
| 16 | 2982616 |
| 17 | 4274361 |
| 18 | 6002157 |
| 19 | 8276590 |
| 20 | 11228070 |
| 21 | 15009071 |
| 22 | 19796491 |
| 23 | 25794132 |
| 24 | 33235300 |
| 25 | 42385525 |
| 26 | 53545401 |
| 27 | 67053546 |
| 28 | 83289682 |
| 29 | 102677835 |
| 30 | 125689655 |
| 31 | 152847856 |
[0,1,21,182,910,3255,9331,22876,49932,99645, 185185,324786,542906,871507,1351455,2034040, 2982616,4274361,6002157,8276590,11228070,15009071, 19796491,25794132,33235300,42385525,53545401, 67053546,83289682,102677835,125689655,152847856] |