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 | 5 |
| 3 | 13 |
| 4 | 137 |
| 5 | 523 |
| 6 | 524309 |
| 7 | 134217757 |
| 8 | 8589934627 |
| 9 | 178405961588244985132285746181186892047843477 |