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 | 3 |
| 1 | 7 |
| 2 | 19 |
| 3 | 47 |
| 4 | 163 |
| 5 | 487 |
| 6 | 1307 |
| 7 | 2879 |
| 8 | 19683 |
| 9 | 39367 |
| 10 | 177147 |
| 11 | 531441 |
| 12 | 1594323 |
| 13 | 4782969 |
| 14 | 14348907 |
| 15 | 43046721 |
| 16 | 86093443 |
| 17 | 258280327 |
| 18 | 688747547 |
| 19 | 3486784401 |
| 20 | 10460353203 |