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 | 0 |
| 2 | 1 |
| 3 | 6 |
| 4 | 37 |
| 5 | 256 |
| 6 | 2000 |
| 7 | 17520 |
| 8 | 170520 |
| 9 | 1827840 |
| 10 | 21409920 |
| 11 | 272160000 |
| 12 | 3732220800 |
| 13 | 54925516800 |
| 14 | 863480217600 |
| 15 | 14442536908800 |
| 16 | 256086230400000 |
| 17 | 4798293147648000 |
| 18 | 94731418349568000 |
| 19 | 1965528727658496000 |