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 | 13 |
| 1 | 55 |
| 2 | 223 |
| 3 | 895 |
| 4 | 3583 |
| 5 | 14335 |
| 6 | 57343 |
| 7 | 229375 |
| 8 | 917503 |
| 9 | 3670015 |
| 10 | 14680063 |
| 11 | 58720255 |
| 12 | 234881023 |
| 13 | 939524095 |
| 14 | 3758096383 |
| 15 | 15032385535 |
| 16 | 60129542143 |
| 17 | 240518168575 |
| 18 | 962072674303 |
| 19 | 3848290697215 |
| 20 | 15393162788863 |
| 21 | 61572651155455 |
| 22 | 246290604621823 |
| 23 | 985162418487295 |