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 | 4 |
| 2 | 5 |
| 3 | 15 |
| 4 | 845 |
| 5 | 403227665 |
| 6 | 64175114443109790962237345 |
| 7 | 264288160993294964501375691029638701718807009656135518176301450923295365341665 |