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 | 2 |
| 3 | 24 |
| 4 | 312 |
| 5 | 4720 |
| 6 | 82800 |
| 7 | 1662024 |
| 8 | 37665152 |
| 9 | 952401888 |
| 10 | 26602156800 |
| 11 | 813815035000 |
| 12 | 27069937855488 |
| 13 | 972940216546896 |
| 14 | 37581134047987712 |
| 15 | 1552687346633913000 |
| 16 | 68331503866677657600 |
| 17 | 3191386068123595166656 |
| 18 | 157663539876436721860608 |