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 | 7 |
| 2 | 50 |
| 3 | 364 |
| 4 | 2696 |
| 5 | 20272 |
| 6 | 154400 |
| 7 | 1188544 |
| 8 | 9228416 |
| 9 | 72147712 |
| 10 | 567104000 |
| 11 | 4476365824 |
| 12 | 35448129536 |
| 13 | 281408253952 |
| 14 | 2238205337600 |
| 15 | 17827278536704 |
| 16 | 142148043309056 |
| 17 | 1134363236564992 |
| 18 | 9057979233075200 |
| 19 | 72362273907933184 |