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 | 0 |
| 2 | 792 |
| 3 | 16704 |
| 4 | 573480 |
| 5 | 6289344 |
| 6 | 47367288 |
| 7 | 256779072 |
| 8 | 1116635400 |
| 9 | 4092791616 |
| 10 | 12993723216 |
| 11 | 37059359040 |
| 12 | 96956352072 |
| 13 | 232789209984 |
| 14 | 526238331840 |
| 15 | 1128121363008 |
| 16 | 2286165374280 |
| 17 | 4451600668032 |
| 18 | 8386296787224 |
| 19 | 15130668404160 |
| 20 | 26614226534832 |
| 21 | 45684867221568 |