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 | 1 |
| 5 | 1 |
| 6 | 1 |
| 7 | 1 |
| 8 | 1 |
| 9 | 45360 |
| 10 | 1 |
| 11 | 1 |
| 12 | 10080 |
| 13 | 7484544 |
| 14 | 20432442240 |
| 15 | 1 |
| 16 | 1 |
| 17 | 226800 |
| 18 | 2554075440 |
| 19 | 29331862801920 |
| 20 | 577185873264000000 |