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) |
|---|---|
| 2 | 1 |
| 3 | 6 |
| 4 | 29 |
| 5 | 131 |
| 6 | 576 |
| 7 | 2505 |
| 8 | 10857 |
| 9 | 47081 |
| 10 | 204724 |
| 11 | 893766 |
| 12 | 3920310 |
| 13 | 17283214 |
| 14 | 76596745 |
| 15 | 341264480 |
| 16 | 1528405584 |
| 17 | 6880122182 |
| 18 | 31123426923 |
| 19 | 141456560459 |
| 20 | 645811464667 |
| 21 | 2960966353657 |
| 22 | 13630215685869 |
| 23 | 62981140857061 |
| 24 | 292049203818249 |