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 | 0 |
| 2 | 6 |
| 3 | 4 |
| 4 | 46 |
| 5 | 12 |
| 6 | 294 |
| 7 | 1908 |
| 8 | 1630 |
| 9 | 13084 |
| 10 | 6486 |
| 11 | 84996 |
| 12 | 517134 |
| 13 | 502828 |
| 14 | 3605638 |
| 15 | 2428308 |
| 16 | 24062142 |
| 17 | 5077564 |
| 18 | 149450422 |
| 19 | 985222180 |
| 20 | 808182894 |
| 21 | 6719515980 |
| 22 | 2978678758 |
| 23 | 43295774644 |
| 24 | 267326277406 |
| 25 | 252223018332 |
| 26 | 1856180682774 |
| 27 | 1170495537220 |