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 | 0 |
| 2 | 0 |
| 3 | 6 |
| 4 | 48 |
| 5 | 360 |
| 6 | 3600 |
| 7 | 45360 |
| 8 | 645120 |
| 9 | 10160640 |
| 10 | 177811200 |
| 11 | 3432844800 |
| 12 | 72329241600 |
| 13 | 1650160512000 |
| 14 | 40537905408000 |
| 15 | 1067062284288000 |
| 16 | 29961435119616000 |
| 17 | 893842506805248000 |
| 18 | 28234468042260480000 |