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 | 0 |
| 3 | 1 |
| 4 | 3 |
| 5 | 13 |
| 6 | 50 |
| 7 | 230 |
| 8 | 1110 |
| 9 | 5787 |
| 10 | 32335 |
| 11 | 191950 |
| 12 | 1206247 |
| 13 | 7997702 |
| 14 | 55733468 |
| 15 | 406952888 |
| 16 | 3105706421 |
| 17 | 24710573792 |
| 18 | 204547052598 |
| 19 | 1758110677909 |
| 20 | 15663244043627 |
| 21 | 144412976181189 |
| 22 | 1375896762258868 |
| 23 | 13528184875421816 |
| 24 | 137098357090429007 |
| 25 | 1430440534060723253 |