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 | 2 |
| 4 | 0 |
| 5 | -11 |
| 6 | 28 |
| 7 | 1 |
| 8 | -206 |
| 9 | 564 |
| 10 | 38 |
| 11 | -4711 |
| 12 | 13329 |
| 13 | 1273 |
| 14 | -119762 |
| 15 | 344707 |
| 16 | 41884 |
| 17 | -3251250 |
| 18 | 9445976 |
| 19 | 1381154 |
| 20 | -92305098 |
| 21 | 269504686 |
| 22 | 45848871 |
| 23 | -2707126108 |
| 24 | 7921304973 |
| 25 | 1532928960 |
| 26 | -81375728566 |
| 27 | 238196143730 |
| 28 | 51591751698 |
| 29 | -2493907008116 |
| 30 | 7293147604136 |