This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 1 |
| 4 | 4 |
| 5 | 5 |
| 6 | 33 |
| 7 | 139 |
| 8 | 515 |
| 9 | 1809 |
| 10 | 6181 |
| 11 | 20759 |
| 12 | 68871 |
| 13 | 226333 |
| 14 | 738089 |
| 15 | 2391459 |
| 16 | 7705867 |
| 17 | 24711977 |
| 18 | 78918957 |
| 19 | 251105839 |