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) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 3 |
| 5 | 6 |
| 6 | 13 |
| 7 | 30 |
| 8 | 72 |
| 9 | 180 |
| 10 | 458 |
| 11 | 1194 |
| 12 | 3160 |
| 13 | 8459 |
| 14 | 22881 |
| 15 | 62417 |
| 16 | 171526 |
| 17 | 474405 |
| 18 | 1319395 |
| 19 | 3687711 |
| 20 | 10352696 |
| 21 | 29178988 |