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 | 2 |
| 2 | 8 |
| 3 | 56 |
| 4 | 576 |
| 5 | 7872 |
| 6 | 134656 |
| 7 | 2771456 |
| 8 | 66744320 |
| 9 | 1842237440 |
| 10 | 57354338304 |
| 11 | 1988721131520 |
| 12 | 76015173369856 |
| 13 | 3175757373243392 |
| 14 | 143980934947930112 |
| 15 | 7040807787705663488 |
| 16 | 369414622819764928512 |
| 17 | 20700889684976244621312 |
| 18 | 1233951687316746828513280 |
| 19 | 77963762014950356953333760 |