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 | 0 |
| 2 | 1 |
| 3 | 5 |
| 4 | 16 |
| 5 | 45 |
| 6 | 126 |
| 7 | 361 |
| 8 | 1046 |
| 9 | 3032 |
| 10 | 8771 |
| 11 | 25348 |
| 12 | 73252 |
| 13 | 211724 |
| 14 | 612009 |
| 15 | 1769080 |
| 16 | 5113647 |
| 17 | 14781237 |
| 18 | 42725841 |
| 19 | 123501151 |
| 20 | 356986401 |
| 21 | 1031887518 |
| 22 | 2982723523 |
| 23 | 8621714049 |
| 24 | 24921502864 |
| 25 | 72036871920 |
| 26 | 208226244217 |
| 27 | 601888555723 |
| 28 | 1739789499591 |
| 29 | 5028950081882 |