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 | 0 |
| 1 | 1 |
| 2 | -3 |
| 3 | 11 |
| 4 | -58 |
| 5 | 409 |
| 6 | -3606 |
| 7 | 38149 |
| 8 | -470856 |
| 9 | 6641793 |
| 10 | -105398650 |
| 11 | 1858413061 |
| 12 | -36044759796 |
| 13 | 762659322385 |
| 14 | -17481598316742 |
| 15 | 431535346662645 |
| 16 | -11413394655983536 |
| 17 | 321989729198400385 |
| 18 | -9651573930139850610 |