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 | 1 |
| 2 | 15 |
| 3 | 21147 |
| 4 | 10480142147 |
| 5 | 4638590332229999353 |
| 6 | 3819714729894818339975525681317 |
| 7 | 10726137154573358400342215518590002633917247281 |