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 | 2 |
| 1 | 12 |
| 2 | 120 |
| 3 | 504 |
| 4 | 1440 |
| 5 | 3168 |
| 6 | 3931200 |
| 7 | 8640 |
| 8 | 41126400 |
| 9 | 579156480 |
| 10 | 2395008000 |
| 11 | 1001548800 |
| 12 | 2615348736000 |
| 13 | 5748019200 |
| 14 | 21670032384000 |
| 15 | 7491404919398400 |
| 16 | 21341245685760000 |
| 17 | 251073478656000 |
| 18 | 24574743184592240640000 |
| 19 | 76828484468736000 |
| 20 | 65834328341259878400000 |