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 | 1 |
| 2 | 4 |
| 3 | 24 |
| 4 | 240 |
| 5 | 4080 |
| 6 | 110880 |
| 7 | 4404960 |
| 8 | 238452480 |
| 9 | 16777393920 |
| 10 | 1484592883200 |
| 11 | 161180605555200 |
| 12 | 21054378333542400 |
| 13 | 3256459844769331200 |
| 14 | 588451470437627596800 |
| 15 | 122827588904844375552000 |