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 | 6 |
| 3 | 42 |
| 4 | 325 |
| 5 | 2688 |
| 6 | 23286 |
| 7 | 208659 |
| 8 | 1918314 |
| 9 | 17994264 |
| 10 | 171542460 |
| 11 | 1657212768 |
| 12 | 16188521454 |
| 13 | 159634359415 |
| 14 | 1586932321578 |
| 15 | 15886925400954 |
| 16 | 160026976985205 |
| 17 | 1620715748715648 |
| 18 | 16493797802077032 |
| 19 | 168583560794745684 |