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 | 0 |
| 3 | -4 |
| 4 | -10 |
| 5 | 2 |
| 6 | 89 |
| 7 | 249 |
| 8 | -91 |
| 9 | -2811 |
| 10 | -8071 |
| 11 | 4201 |
| 12 | 103617 |
| 13 | 297201 |
| 14 | -200421 |
| 15 | -4167581 |
| 16 | -11798389 |
| 17 | 9803475 |
| 18 | 177275251 |
| 19 | 492087227 |
| 20 | -488311177 |
| 21 | -7839760737 |
| 22 | -21249466773 |
| 23 | 24651743523 |
| 24 | 356735365223 |
| 25 | 941396264159 |
| 26 | -1257287146286 |
| 27 | -16589782316762 |