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 | 1 |
| 2 | 1 |
| 3 | 5 |
| 4 | 18 |
| 5 | 66 |
| 6 | 245 |
| 7 | 918 |
| 8 | 3465 |
| 9 | 13156 |
| 10 | 50193 |
| 11 | 192270 |
| 12 | 739024 |
| 13 | 2848860 |
| 14 | 11009778 |
| 15 | 42642460 |
| 16 | 165480975 |
| 17 | 643281480 |
| 18 | 2504501625 |
| 19 | 9764299710 |
| 20 | 38115568260 |
| 21 | 148955040300 |
| 22 | 582714871830 |
| 23 | 2281745337300 |
| 24 | 8942420595810 |
| 25 | 35074414899576 |
| 26 | 137672461877850 |
| 27 | 540756483094828 |