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 | 3 |
| 2 | 9 |
| 3 | 27 |
| 4 | 91 |
| 5 | 325 |
| 6 | 1201 |
| 7 | 4527 |
| 8 | 17227 |
| 9 | 65929 |
| 10 | 252997 |
| 11 | 972339 |
| 12 | 3739775 |
| 13 | 14389629 |
| 14 | 55378713 |
| 15 | 213148903 |
| 16 | 820441299 |
| 17 | 3158089841 |
| 18 | 12156483245 |
| 19 | 46794497819 |
| 20 | 180128888999 |
| 21 | 693382455013 |