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 | 0 |
| 4 | 6 |
| 5 | 0 |
| 6 | 0 |
| 7 | 0 |
| 8 | 1260 |
| 9 | 40320 |
| 10 | 0 |
| 11 | 0 |
| 12 | 1247400 |
| 13 | 172972800 |
| 14 | 6227020800 |
| 15 | 0 |
| 16 | 3405402000 |
| 17 | 1235025792000 |
| 18 | 153848927232000 |
| 19 | 6402373705728000 |
| 20 | 19799007228000 |
| 21 | 14783258730240000 |
| 22 | 4243499220280320000 |
| 23 | 545332851008225280000 |
| 24 | 25852227123135781368000 |