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) |
|---|---|
| 1 | 1 |
| 2 | -1 |
| 3 | 0 |
| 4 | 3 |
| 5 | -8 |
| 6 | 12 |
| 7 | -6 |
| 8 | -37 |
| 9 | 208 |
| 10 | -730 |
| 11 | 1708 |
| 12 | -1278 |
| 13 | -10018 |
| 14 | 56782 |
| 15 | -163644 |
| 16 | 229985 |
| 17 | 389830 |
| 18 | -3724538 |
| 19 | 13460550 |
| 20 | -28799694 |
| 21 | 12470564 |
| 22 | 205544596 |
| 23 | -1084748334 |
| 24 | 3195484242 |
| 25 | -4851317704 |
| 26 | -7421547798 |
| 27 | 81343472008 |