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) |
|---|---|
| 3 | 1 |
| 4 | 0 |
| 5 | 18 |
| 6 | -19 |
| 7 | 185 |
| 8 | -294 |
| 9 | 1463 |
| 10 | -2715 |
| 11 | 9648 |
| 12 | -19005 |
| 13 | 55413 |
| 14 | -111069 |
| 15 | 284560 |
| 16 | -568913 |
| 17 | 1331790 |
| 18 | -2630648 |
| 19 | 5761619 |
| 20 | -11195907 |
| 21 | 23296840 |
| 22 | -44461191 |
| 23 | 88813155 |
| 24 | -166422196 |
| 25 | 321471340 |
| 26 | -591712017 |
| 27 | 1111195198 |
| 28 | -2010602744 |
| 29 | 3685487712 |
| 30 | -6561391792 |
| 31 | 11775930023 |
| 32 | -20647946256 |
| 33 | 36371943075 |