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) |
|---|---|
| 1 | 3 |
| 2 | 9 |
| 3 | 25 |
| 4 | 75 |
| 5 | 213 |
| 6 | 621 |
| 7 | 1801 |
| 8 | 5219 |
| 9 | 15133 |
| 10 | 43867 |
| 11 | 127195 |
| 12 | 368759 |
| 13 | 1069105 |
| 14 | 3099583 |
| 15 | 8986391 |
| 16 | 26053581 |
| 17 | 75535111 |
| 18 | 218993223 |
| 19 | 634910491 |
| 20 | 1840747761 |
| 21 | 5336740123 |
| 22 | 15472405305 |
| 23 | 44857970049 |
| 24 | 130053306249 |
| 25 | 377053674603 |
| 26 | 1093163086545 |