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 | 0 |
| 1 | 1 |
| 2 | 3 |
| 3 | 9 |
| 4 | 39 |
| 5 | 1089 |
| 6 | 70814494839 |
| 7 | 7568077812763134673885891483463343434987134201379042046671543939118568810481776089 |