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 | 0 |
| 2 | 1 |
| 3 | 5 |
| 4 | 41 |
| 5 | 394 |
| 6 | 4704 |
| 7 | 65386 |
| 8 | 1049754 |
| 9 | 19032392 |
| 10 | 385419072 |
| 11 | 8615947592 |
| 12 | 210831826952 |
| 13 | 5604404196832 |
| 14 | 160834760288864 |
| 15 | 4955867959526784 |
| 16 | 163197046787269792 |
| 17 | 5719576163352685696 |
| 18 | 212565832527352216928 |
| 19 | 8350117027586731306848 |