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 | 0 |
| 5 | 24 |
| 6 | 720 |
| 7 | 17640 |
| 8 | 430080 |
| 9 | 11022480 |
| 10 | 302835456 |
| 11 | 8976567600 |
| 12 | 287236730880 |
| 13 | 9901354268520 |
| 14 | 366504424366080 |
| 15 | 14515574208519384 |
| 16 | 612912858447052800 |
| 17 | 27497080096591516320 |
| 18 | 1306520704652165775360 |
| 19 | 65556843230110158804960 |
| 20 | 3464412427539012262035456 |