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 | 3 |
| 3 | 7 |
| 4 | 21 |
| 5 | 57 |
| 6 | 169 |
| 7 | 507 |
| 8 | 1515 |
| 9 | 4543 |
| 10 | 13629 |
| 11 | 40881 |
| 12 | 122641 |
| 13 | 367923 |
| 14 | 1103763 |
| 15 | 3311287 |
| 16 | 9933861 |
| 17 | 29801577 |
| 18 | 89404729 |
| 19 | 268214187 |
| 20 | 804642555 |
| 21 | 2413927663 |
| 22 | 7241782989 |
| 23 | 21725348961 |
| 24 | 65176046881 |
| 25 | 195528140643 |
| 26 | 586584421923 |