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 | 3 |
| 3 | 12 |
| 4 | 23 |
| 5 | 94 |
| 6 | 289 |
| 7 | 842 |
| 8 | 2771 |
| 9 | 8510 |
| 10 | 26411 |
| 11 | 83122 |
| 12 | 258199 |
| 13 | 805914 |
| 14 | 2517287 |
| 15 | 7846960 |
| 16 | 24490017 |
| 17 | 76416244 |
| 18 | 238387767 |
| 19 | 743840496 |
| 20 | 2320800841 |
| 21 | 7240890040 |
| 22 | 22592311143 |
| 23 | 70488834118 |
| 24 | 219928631821 |
| 25 | 686190651342 |
| 26 | 2140948175385 |
| 27 | 6679872756528 |
| 28 | 20841562274863 |