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 | 8 |
| 3 | 120 |
| 4 | 1680 |
| 5 | 23408 |
| 6 | 326040 |
| 7 | 4541160 |
| 8 | 63250208 |
| 9 | 880961760 |
| 10 | 12270214440 |
| 11 | 170902040408 |
| 12 | 2380358351280 |
| 13 | 33154114877520 |
| 14 | 461777249934008 |
| 15 | 6431727384198600 |
| 16 | 89582406128846400 |
| 17 | 1247721958419651008 |
| 18 | 17378525011746267720 |
| 19 | 242051628206028097080 |
| 20 | 3371344269872647091408 |