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 | 0 |
| 1 | 2 |
| 2 | 4 |
| 3 | 32 |
| 4 | 128 |
| 5 | 1152 |
| 6 | 6912 |
| 7 | 73728 |
| 8 | 589824 |
| 9 | 7372800 |
| 10 | 73728000 |
| 11 | 1061683200 |
| 12 | 12740198400 |
| 13 | 208089907200 |
| 14 | 2913258700800 |
| 15 | 53271016243200 |
| 16 | 852336259891200 |
| 17 | 17259809262796800 |
| 18 | 310676566730342400 |
| 19 | 6903923705118720000 |
| 20 | 138078474102374400000 |
| 21 | 3341499073277460480000 |