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 | 3 |
| 1 | 15 |
| 2 | 525 |
| 3 | 1414875 |
| 4 | 41985913344375 |
| 5 | 433555011900329243987584396875 |
| 6 | 3514495551481947615680580256869117013417604971088496013610671875 |