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 | 1 |
| 1 | 9 |
| 2 | 129 |
| 3 | 1537 |
| 4 | 16385 |
| 5 | 163841 |
| 6 | 1572865 |
| 7 | 14680065 |
| 8 | 134217729 |
| 9 | 1207959553 |
| 10 | 10737418241 |
| 11 | 94489280513 |
| 12 | 824633720833 |
| 13 | 7146825580545 |
| 14 | 61572651155457 |
| 15 | 527765581332481 |
| 16 | 4503599627370497 |
| 17 | 38280596832649217 |
| 18 | 324259173170675713 |
| 19 | 2738188573441261569 |
| 20 | 23058430092136939521 |