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) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 12 |
| 3 | 84 |
| 4 | 588 |
| 5 | 4116 |
| 6 | 28812 |
| 7 | 201684 |
| 8 | 1411788 |
| 9 | 9882516 |
| 10 | 69177612 |
| 11 | 484243284 |
| 12 | 3389702988 |
| 13 | 23727920916 |
| 14 | 166095446412 |
| 15 | 1162668124884 |
| 16 | 8138676874188 |
| 17 | 56970738119316 |
| 18 | 398795166835212 |
| 19 | 2791566167846484 |
| 20 | 19540963174925388 |