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 | 23 |
| 3 | 192 |
| 4 | 2184 |
| 5 | 31728 |
| 6 | 560412 |
| 7 | 11630592 |
| 8 | 276921216 |
| 9 | 7433925120 |
| 10 | 222038547840 |
| 11 | 7301712936960 |
| 12 | 262112637864960 |
| 13 | 10198096116526080 |
| 14 | 427456901317420800 |
| 15 | 19202256562264473600 |
| 16 | 920321900537337446400 |
| 17 | 46874495077202077286400 |
| 18 | 2528269620326135923507200 |