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 | 17 |
| 3 | 51 |
| 4 | 417 |
| 5 | 1251 |
| 6 | 7089 |
| 7 | 21267 |
| 8 | 206657 |
| 9 | 619971 |
| 10 | 3513169 |
| 11 | 10539507 |
| 12 | 86175969 |
| 13 | 258527907 |
| 14 | 1464991473 |
| 15 | 4394974419 |
| 16 | 44854599297 |
| 17 | 134563797891 |
| 18 | 762528188049 |
| 19 | 2287584564147 |
| 20 | 18704367906849 |
| 21 | 56113103720547 |
| 22 | 317974254416433 |
| 23 | 953922763249299 |
| 24 | 9269516926920129 |