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 | 4 |
| 2 | 14 |
| 3 | 60 |
| 4 | 312 |
| 5 | 1920 |
| 6 | 13680 |
| 7 | 110880 |
| 8 | 1008000 |
| 9 | 10160640 |
| 10 | 112492800 |
| 11 | 1357171200 |
| 12 | 17723059200 |
| 13 | 249080832000 |
| 14 | 3748666521600 |
| 15 | 60153020928000 |
| 16 | 1025216704512000 |
| 17 | 18495746260992000 |
| 18 | 352130553815040000 |
| 19 | 7055415823712256000 |