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 | 60 |
| 6 | 480 |
| 7 | 5250 |
| 8 | 40656 |
| 9 | 302904 |
| 10 | 3024720 |
| 11 | 35260830 |
| 12 | 400499880 |
| 13 | 4619610996 |
| 14 | 58758862344 |
| 15 | 813678468330 |
| 16 | 11686918766880 |
| 17 | 173172973038960 |
| 18 | 2695921067029536 |
| 19 | 44219170187746614 |
| 20 | 755363769931590840 |
| 21 | 13351503268881437100 |
| 22 | 244634794020399856920 |