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 | 0 |
| 2 | 488 |
| 3 | 0 |
| 4 | 11660 |
| 5 | 375552 |
| 6 | 0 |
| 7 | 160680 |
| 8 | 6652366 |
| 9 | 146387872 |
| 10 | 0 |
| 11 | 1678880 |
| 12 | 86303920 |
| 13 | 2298445830 |
| 14 | 42795288180 |
| 15 | 0 |
| 16 | 14771680 |
| 17 | 918342738 |
| 18 | 28995928200 |
| 19 | 629732269188 |
| 20 | 10663498973088 |