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 | 1 |
| 2 | 1 |
| 3 | -4 |
| 4 | -51 |
| 5 | -304 |
| 6 | 125 |
| 7 | 34880 |
| 8 | 557753 |
| 9 | 3416320 |
| 10 | -74779911 |
| 11 | -2917151744 |
| 12 | -46015368443 |
| 13 | 115191402496 |
| 14 | 30429734385973 |
| 15 | 942941062774784 |
| 16 | 9925460231059185 |
| 17 | -471696770041053184 |
| 18 | -29508689065235461903 |
| 19 | -733077456673636089856 |
| 20 | 4714209123766494329021 |