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 | 1 |
| 3 | 1 |
| 4 | 2 |
| 5 | 6 |
| 6 | 24 |
| 7 | 2520 |
| 8 | 18378360 |
| 9 | 6906955255200 |
| 10 | 5987137029832314231356979603166508647200 |
| 11 | 1000156941827668764767034398758639477404906113721462819980559968765060862592344000 |