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 | 18 |
| 3 | 588 |
| 4 | 30240 |
| 5 | 2277600 |
| 6 | 234440280 |
| 7 | 31448589480 |