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 | 2 |
| 3 | 18 |
| 4 | 144 |
| 5 | 1200 |
| 6 | 10800 |
| 7 | 105840 |
| 8 | 1128960 |
| 9 | 13063680 |
| 10 | 163296000 |
| 11 | 2195424000 |
| 12 | 31614105600 |
| 13 | 485707622400 |
| 14 | 7933224499200 |
| 15 | 137305808640000 |
| 16 | 2510734786560000 |
| 17 | 48373490221056000 |
| 18 | 979563176976384000 |
| 19 | 20801312169910272000 |
| 20 | 462251381553561600000 |