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) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 20 |
| 4 | 276 |
| 5 | 10688 |
| 6 | 1601952 |
| 7 | 892341888 |
| 8 | 1799786093088 |
| 9 | 13042490003160192 |
| 10 | 341378170022783017472 |
| 11 | 32526326484972756063585792 |
| 12 | 11367103329997359707194173746176 |
| 13 | 14669222110846093400698801891700529152 |