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 | 24 |
| 5 | 0 |
| 6 | 360 |
| 7 | 5040 |
| 8 | 20160 |
| 9 | 60480 |
| 10 | 1814400 |
| 11 | 19958400 |
| 12 | 99792000 |
| 13 | 1037836800 |
| 14 | 21794572800 |
| 15 | 228843014400 |
| 16 | 1743565824000 |
| 17 | 29640619008000 |
| 18 | 542423327846400 |
| 19 | 6082255020441600 |
| 20 | 70959641905152000 |
| 21 | 1429329929803776000 |
| 22 | 24977793950613504000 |