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 | 252 |
| 3 | 756756 |
| 4 | 11732745024 |
| 5 | 52977847995072 |
| 6 | 131319696504676680 |
| 7 | 302061042944500510428 |
| 8 | 847432462636241316703042 |