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 | 0 |
| 5 | 60 |
| 6 | 360 |
| 7 | 1680 |
| 8 | 20160 |
| 9 | 151200 |
| 10 | 1663200 |
| 11 | 17962560 |
| 12 | 219542400 |
| 13 | 2854051200 |
| 14 | 40441040640 |
| 15 | 606356150400 |
| 16 | 9793028044800 |
| 17 | 166481476761600 |
| 18 | 3017626733721600 |
| 19 | 57359043873331200 |
| 20 | 1153275200453376000 |
| 21 | 24233844054131712000 |
| 22 | 535361100608439705600 |