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 | 0 |
| 2 | -4 |
| 3 | 18 |
| 4 | -64 |
| 5 | 210 |
| 6 | -664 |
| 7 | 2058 |
| 8 | -6304 |
| 9 | 19170 |
| 10 | -58024 |
| 11 | 175098 |
| 12 | -527344 |
| 13 | 1586130 |
| 14 | -4766584 |
| 15 | 14316138 |
| 16 | -42981184 |
| 17 | 129009090 |
| 18 | -387158344 |
| 19 | 1161737178 |
| 20 | -3485735824 |
| 21 | 10458256050 |
| 22 | -31376865304 |
| 23 | 94134790218 |
| 24 | -282412759264 |
| 25 | 847255055010 |
| 26 | -2541798719464 |
| 27 | 7625463267258 |