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 | 3 |
| 2 | 10 |
| 3 | 37 |
| 4 | 149 |
| 5 | 648 |
| 6 | 3039 |
| 7 | 15401 |
| 8 | 84619 |
| 9 | 505500 |
| 10 | 3287256 |
| 11 | 23250514 |
| 12 | 178382427 |
| 13 | 1478782490 |
| 14 | 13187788246 |
| 15 | 125958159631 |
| 16 | 1283067859947 |
| 17 | 13886218459612 |
| 18 | 159124624924418 |
| 19 | 1924735353849082 |
| 20 | 24506483918914367 |
| 21 | 327627501208785322 |