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 | 24 |
| 6 | 73 |
| 7 | 171 |
| 8 | 500 |
| 9 | 1276 |
| 10 | 3698 |
| 11 | 9588 |
| 12 | 28119 |
| 13 | 75094 |
| 14 | 217835 |
| 15 | 599077 |
| 16 | 1736639 |
| 17 | 4842231 |
| 18 | 14092249 |
| 19 | 39844806 |
| 20 | 116011719 |
| 21 | 331986975 |
| 22 | 969188079 |
| 23 | 2796468133 |
| 24 | 8188982136 |
| 25 | 23798219204 |
| 26 | 69884802788 |
| 27 | 204303838580 |
| 28 | 601666227876 |
| 29 | 1767334874977 |
| 30 | 5219585473815 |
[1,1,2,4,11,24,73,171,500,1276,3698,9588,28119, 75094,217835,599077,1736639,4842231,14092249, 39844806,116011719,331986975,969188079,2796468133, 8188982136,23798219204,69884802788,204303838580, 601666227876,1767334874977,5219585473815] |