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 | 7 |
| 2 | 2047 |
| 3 | 402653183 |
| 4 | 1180591620717411303423 |
| 5 | 233840261972944466912589573234605283144949206876159 |