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 | 5 |
| 2 | 21 |
| 3 | 89 |
| 4 | 377 |
| 5 | 1569 |
| 6 | 6425 |
| 7 | 26033 |
| 8 | 104841 |
| 9 | 420833 |
| 10 | 1686329 |
| 11 | 6751377 |
| 12 | 27017705 |
| 13 | 108095297 |
| 14 | 432430233 |
| 15 | 1729819121 |