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) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 5 |
| 4 | 51 |
| 5 | 757 |
| 6 | 16416 |
| 7 | 461231 |
| 8 | 16021550 |
| 9 | 662197510 |
| 10 | 31749450007 |
| 11 | 1732478051823 |
| 12 | 106025572201434 |
| 13 | 7192665669790893 |
| 14 | 535756912504764218 |
| 15 | 43471544417828923777 |
| 16 | 3816784803681841133512 |
| 17 | 360546156617986177328681 |
| 18 | 36462349359125513109697520 |
| 19 | 3930704977357944446111295571 |