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 | 1 |
| 3 | 4 |
| 4 | 20 |
| 5 | 15700 |
| 6 | 161520 |
| 7 | 659739168 |
| 8 | 11887243200 |
| 9 | 115875912594352 |
| 10 | 1360481062410358294032 |
| 11 | 40999220870977029249072 |
| 12 | 1854483563489396099991763032000 |
| 13 | 106016408292727234808287504322403328 |
| 14 | 4534810991759912394035394805790730240 |