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 | 3 |
| 3 | 7 |
| 4 | -55 |
| 5 | -1215 |
| 6 | -8645 |
| 7 | 150535 |
| 8 | 6200145 |
| 9 | 73698625 |
| 10 | -1986309325 |
| 11 | -119693799225 |
| 12 | -1993326710375 |
| 13 | 72724743316225 |
| 14 | 5768642653648875 |
| 15 | 123556356142594375 |
| 16 | -5685256808745889375 |
| 17 | -559310285769833973375 |
| 18 | -14644269999088713108125 |
| 19 | 813361265343230663434375 |