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 | 127 |
| 3 | 1535 |
| 4 | 16383 |
| 5 | 163839 |
| 6 | 1572863 |
| 7 | 14680063 |
| 8 | 134217727 |
| 9 | 1207959551 |
| 10 | 10737418239 |
| 11 | 94489280511 |
| 12 | 824633720831 |
| 13 | 7146825580543 |
| 14 | 61572651155455 |
| 15 | 527765581332479 |
| 16 | 4503599627370495 |
| 17 | 38280596832649215 |
| 18 | 324259173170675711 |
| 19 | 2738188573441261567 |
| 20 | 23058430092136939519 |