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 | 0 |
| 1 | 4 |
| 2 | 48 |
| 3 | 480 |
| 4 | 4560 |
| 5 | 42504 |
| 6 | 393120 |
| 7 | 3624768 |
| 8 | 33390720 |
| 9 | 307618740 |
| 10 | 2835722032 |
| 11 | 26162863584 |
| 12 | 241614915360 |
| 13 | 2233533229200 |
| 14 | 20667453710400 |
| 15 | 191422799835264 |
| 16 | 1774573628661504 |
| 17 | 16465220088660432 |
| 18 | 152894968403313600 |
| 19 | 1420856831349155200 |
| 20 | 13213537097286612240 |