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 | 1 |
| 2 | -7 |
| 3 | -15 |
| 4 | 41 |
| 5 | 161 |
| 6 | -167 |
| 7 | -1455 |
| 8 | -119 |
| 9 | 11521 |
| 10 | 12473 |
| 11 | -79695 |
| 12 | -179479 |
| 13 | 458081 |
| 14 | 1893913 |
| 15 | -1770735 |
| 16 | -16922039 |
| 17 | -2756159 |
| 18 | 132620153 |
| 19 | 154669425 |
| 20 | -906291799 |
| 21 | -2143647199 |
| 22 | 5106687193 |
| 23 | 22255864785 |
| 24 | -18597632759 |
| 25 | -196644551039 |
| 26 | -47863488967 |
| 27 | 1525292919345 |