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 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 6 |
| 5 | 18 |
| 6 | 62 |
| 7 | 186 |
| 8 | 570 |
| 9 | 1680 |
| 10 | 4890 |
| 11 | 14058 |
| 12 | 40200 |
| 13 | 114450 |
| 14 | 325230 |
| 15 | 923846 |
| 16 | 2624730 |
| 17 | 7465410 |
| 18 | 21260652 |
| 19 | 60647370 |
| 20 | 173288724 |
| 21 | 496014934 |
| 22 | 1422211494 |
| 23 | 4084793082 |
| 24 | 11751102060 |
| 25 | 33857989968 |
| 26 | 97696908330 |
| 27 | 282295318536 |
| 28 | 816759712080 |
| 29 | 2366027865810 |
| 30 | 6861963548198 |
| 31 | 19922800783578 |
| 32 | 57902584654650 |