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 | 5 |
| 3 | 105 |
| 4 | 4116 |
| 5 | 232848 |
| 6 | 16818516 |
| 7 | 1447482465 |
| 8 | 142174944340 |
| 9 | 15484613937936 |
| 10 | 1832516612010448 |
| 11 | 232187445047217296 |
| 12 | 31148053701600494400 |