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 | 240 |
| 4 | 16800 |
| 5 | 4233600 |
| 6 | 3911846400 |
| 7 | 13425456844800 |
| 8 | 172785629592576000 |
| 9 | 8400837310791045120000 |
| 10 | 1552105098192510332190720000 |
| 11 | 1094904603628138948657963991040000 |
| 12 | 2960792853328653706847125274154762240000 |
| 13 | 30794022150329995743434211126374020153344000000 |