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 | -4 |
| 4 | 17 |
| 5 | -56 |
| 6 | 172 |
| 7 | -547 |
| 8 | 1809 |
| 9 | -6061 |
| 10 | 20316 |
| 11 | -68135 |
| 12 | 229244 |
| 13 | -774372 |
| 14 | 2624119 |
| 15 | -8912759 |
| 16 | 30328593 |
| 17 | -103382254 |
| 18 | 352975681 |
| 19 | -1206921212 |
| 20 | 4132159452 |
| 21 | -14163858895 |
| 22 | 48601267199 |
| 23 | -166930975524 |
| 24 | 573872089212 |
| 25 | -1974472043081 |
| 26 | 6798561779868 |
| 27 | -23425506369715 |