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 | -3 |
| 2 | 13 |
| 3 | -52 |
| 4 | 211 |
| 5 | -854 |
| 6 | 3458 |
| 7 | -14001 |
| 8 | 56689 |
| 9 | -229529 |
| 10 | 929344 |
| 11 | -3762837 |
| 12 | 15235416 |
| 13 | -61686940 |
| 14 | 249765321 |
| 15 | -1011279139 |
| 16 | 4094585641 |
| 17 | -16578638800 |
| 18 | 67125538103 |
| 19 | -271785755150 |
| 20 | 1100438056662 |
| 21 | -4455582728689 |
| 22 | 18040286167865 |
| 23 | -73043627475013 |
| 24 | 295747609825188 |
| 25 | -1197457625543481 |