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 | 4 |
| 3 | 20 |
| 4 | 223 |
| 5 | 3227 |
| 6 | 77194 |
| 7 | 2097080 |
| 8 | 57796870 |
| 9 | 1502295684 |
| 10 | 36065804158 |
| 11 | 795109767172 |
| 12 | 16115614918786 |
| 13 | 301341514055753 |
| 14 | 5220182848555434 |
| 15 | 84132279974374399 |