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 | 12 |
| 3 | 120 |
| 4 | 5040 |
| 5 | 110880 |
| 6 | 43243200 |
| 7 | 1470268800 |
| 8 | 1173274502400 |
| 9 | 269853135552000 |
| 10 | 516498901446528000 |
| 11 | 32022931889684736000 |
| 12 | 3234636350177055183360000 |
| 13 | 265240180714518525035520000 |
| 14 | 1163343432613878250805790720000 |
| 15 | 6014485546613750556665938022400000 |