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 | 15 |
| 2 | 225 |
| 3 | 229503 |
| 4 | 42980713761 |
| 5 | 1380524064964529355 |
| 6 | 7955148565342992851131291305 |