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 | 4 |
| 2 | 15 |
| 3 | 53 |
| 4 | 187 |
| 5 | 656 |
| 6 | 2301 |
| 7 | 8071 |
| 8 | 28308 |
| 9 | 99293 |
| 10 | 348275 |
| 11 | 1221603 |
| 12 | 4284864 |
| 13 | 15029495 |
| 14 | 52717114 |
| 15 | 184909361 |
| 16 | 648583888 |
| 17 | 2274958177 |
| 18 | 7979591823 |
| 19 | 27989035739 |
| 20 | 98173708464 |
| 21 | 344351878525 |
| 22 | 1207840857737 |
| 23 | 4236595263812 |
| 24 | 14860185689435 |
| 25 | 52123251095327 |