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 | 0 |
| 1 | 0 |
| 2 | 2 |
| 3 | 6 |
| 4 | 16 |
| 5 | 40 |
| 6 | 98 |
| 7 | 238 |
| 8 | 576 |
| 9 | 1392 |
| 10 | 3362 |
| 11 | 8118 |
| 12 | 19600 |
| 13 | 47320 |
| 14 | 114242 |
| 15 | 275806 |
| 16 | 665856 |
| 17 | 1607520 |
| 18 | 3880898 |
| 19 | 9369318 |
| 20 | 22619536 |
| 21 | 54608392 |
| 22 | 131836322 |
| 23 | 318281038 |
| 24 | 768398400 |
| 25 | 1855077840 |
| 26 | 4478554082 |
| 27 | 10812186006 |
| 28 | 26102926096 |
| 29 | 63018038200 |
| 30 | 152139002498 |