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 | 3 |
| 2 | 19 |
| 3 | 211 |
| 4 | 1249 |
| 5 | 4513 |
| 6 | 1445953 |
| 7 | 30381331 |
| 8 | 286292179 |
| 9 | 2959257735801707821729 |