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) |
|---|---|
| 2 | 1 |
| 3 | 4 |
| 4 | 36 |
| 5 | 144 |
| 6 | 1800 |
| 7 | 43200 |
| 8 | 705600 |
| 9 | 705600 |
| 10 | 2116800 |
| 11 | 127008000 |
| 12 | 23051952000 |
| 13 | 6638962176000 |
| 14 | 280496151936000 |
| 15 | 31415569016832000 |
| 16 | 471233535252480000 |
| 17 | 471233535252480000 |
| 18 | 54474596675186688000 |
| 19 | 3268475800511201280000 |