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 | -2 |
| 3 | -2 |
| 4 | 7 |
| 5 | 78 |
| 6 | 513 |
| 7 | 2665 |
| 8 | 9406 |
| 9 | -13902 |
| 10 | -789143 |
| 11 | -11806456 |
| 12 | -140040408 |
| 13 | -1463842226 |
| 14 | -13377115923 |
| 15 | -95264642343 |
| 16 | -198034245627 |
| 17 | 11021440199748 |
| 18 | 322964047973519 |
| 19 | 6617250866231379 |
| 20 | 118668721540190350 |
| 21 | 1965786734149801960 |
| 22 | 30348547043773563767 |