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 | 6 |
| 3 | 12 |
| 4 | 24 |
| 5 | 54 |
| 6 | 138 |
| 7 | 378 |
| 8 | 1080 |
| 9 | 3186 |
| 10 | 9642 |
| 11 | 29784 |
| 12 | 93552 |
| 13 | 297966 |
| 14 | 960294 |
| 15 | 3126408 |
| 16 | 10268688 |
| 17 | 33989388 |
| 18 | 113277582 |
| 19 | 379833906 |
| 20 | 1280618784 |
| 21 | 4339003044 |
| 22 | 14767407522 |
| 23 | 50464951224 |
| 24 | 173099580168 |
| 25 | 595786322292 |
| 26 | 2057106617226 |
| 27 | 7123467773790 |
| 28 | 24734460619704 |