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 | 4 |
| 1 | 15 |
| 2 | 223 |
| 3 | 49726 |
| 4 | 2472675072 |
| 5 | 6114122011690205179 |
| 6 | 37382487973834681475536573127118422035 |
| 7 | 1397450407113894589170760370457882734663916414838438245542265330668373541218 |