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 | 1 |
| 2 | 0 |
| 3 | 6 |
| 4 | 24 |
| 5 | 120 |
| 6 | 720 |
| 7 | 5040 |
| 8 | 80640 |
| 9 | 725760 |
| 10 | 7257600 |
| 11 | 79833600 |
| 12 | 1437004800 |
| 13 | 18681062400 |
| 14 | 261534873600 |
| 15 | 5230697472000 |
| 16 | 104613949440000 |
| 17 | 1778437140480000 |
| 18 | 32011868528640000 |
| 19 | 729870602452992000 |
| 20 | 17030314057236480000 |
| 21 | 408727537373675520000 |
| 22 | 8992005822220861440000 |