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 | -1 |
| 3 | 3 |
| 4 | -4 |
| 5 | -9 |
| 6 | 73 |
| 7 | -212 |
| 8 | 111 |
| 9 | 1956 |
| 10 | -10078 |
| 11 | 21466 |
| 12 | 29823 |
| 13 | -418183 |
| 14 | 1561911 |
| 15 | -1722963 |
| 16 | -13205004 |
| 17 | 86962328 |
| 18 | -232448945 |
| 19 | -109578204 |
| 20 | 3849218852 |
| 21 | -17135183489 |
| 22 | 27800381006 |
| 23 | 113891855632 |
| 24 | -966644138742 |
| 25 | 3075070731677 |
| 26 | -833503324311 |
| 27 | -41673632701038 |