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 | 1 |
| 2 | 4 |
| 3 | 19 |
| 4 | 109 |
| 5 | 742 |
| 6 | 5815 |
| 7 | 51193 |
| 8 | 498118 |
| 9 | 5296321 |
| 10 | 60987817 |
| 11 | 754940848 |
| 12 | 9983845261 |
| 13 | 140329768789 |
| 14 | 2087182244308 |
| 15 | 32725315072135 |
| 16 | 539118388883449 |
| 17 | 9304591246975030 |
| 18 | 167804098493079547 |
| 19 | 3155000165773280893 |