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 | 2 |
| 2 | 5 |
| 3 | 18 |
| 4 | 91 |
| 5 | 592 |
| 6 | 4643 |
| 7 | 42276 |
| 8 | 436629 |
| 9 | 5033182 |
| 10 | 63974273 |
| 11 | 888047414 |
| 12 | 13358209647 |
| 13 | 216334610860 |
| 14 | 3751352135263 |
| 15 | 69325155322184 |
| 16 | 1359759373992105 |
| 17 | 28206375825238458 |
| 18 | 616839844140642301 |
| 19 | 14181213537729200474 |
| 20 | 341879141423814854915 |
| 21 | 8623032181189674581256 |