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 | 2 |
| 1 | 9 |
| 2 | 45 |
| 3 | 243 |
| 4 | 1377 |
| 5 | 8019 |
| 6 | 47385 |
| 7 | 282123 |
| 8 | 1686177 |
| 9 | 10097379 |
| 10 | 60525225 |
| 11 | 362974203 |
| 12 | 2177313777 |
| 13 | 13062288339 |
| 14 | 78368947065 |
| 15 | 470199333483 |
| 16 | 2821152954177 |
| 17 | 16926788584899 |
| 18 | 101560344088905 |
| 19 | 609360902271963 |
| 20 | 3656161926847377 |