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 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 41 |
| 5 | 842 |
| 6 | 20520 |
| 7 | 477479 |
| 8 | 12482191 |
| 9 | 344597977 |
| 10 | 10325683780 |
| 11 | 329996493091 |
| 12 | 11307950123833 |
| 13 | 411428962250775 |
| 14 | 15890609817681079 |
| 15 | 648195555340597125 |
| 16 | 27864181100124570327 |
| 17 | 1258096888119566215689 |
| 18 | 59531788666265363070393 |
| 19 | 2944807922604446013781174 |