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 | 7 |
| 4 | 9 |
| 5 | 11 |
| 6 | 15 |
| 7 | 19 |
| 8 | 23 |
| 9 | 63 |
| 10 | 159 |
| 11 | 2047 |
| 12 | 10239 |
| 13 | 49151 |
| 14 | 1048575 |
| 15 | 20971519 |
| 16 | 402653183 |
| 17 | 1180591620717411303423 |
| 18 | 233840261972944466912589573234605283144949206876159 |