The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 11 |
| 5 | 26 |
| 6 | 75 |
| 7 | 216 |
| 8 | 656 |
| 9 | 1950 |
| 10 | 6394 |
| 11 | 20193 |
| 12 | 66477 |
| 13 | 219595 |
| 14 | 751938 |
| 15 | 2514386 |
| 16 | 8774087 |
| 17 | 30337633 |
| 18 | 106836045 |
| 19 | 374070118 |
| 20 | 1345890867 |
| 21 | 4774149535 |
| 22 | 17280927737 |
| 23 | 62313709836 |
| 24 | 227984366294 |
| 25 | 827225060479 |
| 26 | 3057313053045 |
| 27 | 11215364858889 |
| 28 | 41639840450091 |
| 29 | 153962548708726 |
| 30 | 576444836942769 |
| 31 | 2143059863393340 |
[1,1,2,4,11,26,75,216,656,1950,6394,20193,66477, 219595,751938,2514386,8774087,30337633,106836045, 374070118,1345890867,4774149535,17280927737, 62313709836,227984366294,827225060479, 3057313053045,11215364858889,41639840450091, 153962548708726,576444836942769,2143059863393340] |