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 | 2 |
| 2 | -1 |
| 3 | 3 |
| 4 | -11 |
| 5 | 44 |
| 6 | -187 |
| 7 | 827 |
| 8 | -3751 |
| 9 | 17313 |
| 10 | -81004 |
| 11 | 383390 |
| 12 | -1833029 |
| 13 | 8843224 |
| 14 | -43007753 |
| 15 | 210670655 |
| 16 | -1038597645 |
| 17 | 5149654796 |
| 18 | -25664518105 |
| 19 | 128493771585 |
| 20 | -645988558986 |
| 21 | 3259776393676 |
| 22 | -16505191207192 |
| 23 | 83828620957326 |
| 24 | -426961815072785 |