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) |
|---|---|
| 4 | 16 |
| 5 | 50 |
| 6 | 406 |
| 7 | 1258008 |
| 8 | 25465014649108 |
| 9 | 208080288305986199465852412572946560 |