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 | -2 |
| 4 | -59 |
| 5 | -744 |
| 6 | -6419 |
| 7 | -6096 |
| 8 | 1504553 |
| 9 | 47199232 |
| 10 | 911415481 |
| 11 | 7309642880 |
| 12 | -338340409043 |
| 13 | -21607316073472 |
| 14 | -725479564376475 |
| 15 | -13094500078091264 |
| 16 | 245361657851526353 |
| 17 | 35579148236923486208 |
| 18 | 1875350389057457406193 |
| 19 | 57582879572195726819328 |