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 | 0 |
| 2 | 2 |
| 3 | 3 |
| 4 | 12 |
| 5 | 23 |
| 6 | 84 |
| 7 | 204 |
| 8 | 682 |
| 9 | 1977 |
| 10 | 6546 |
| 11 | 21003 |
| 12 | 72038 |
| 13 | 248055 |
| 14 | 888771 |
| 15 | 3240578 |
| 16 | 12152775 |
| 17 | 46527471 |
| 18 | 182339441 |
| 19 | 729405164 |
| 20 | 2979121279 |
| 21 | 12407308136 |
| 22 | 52670355242 |
| 23 | 227725915268 |
| 24 | 1002285274515 |
| 25 | 4487915293698 |
| 26 | 20434064295155 |
| 27 | 94559526596293 |
| 28 | 444527730210294 |
| 29 | 2122005930659752 |