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 | 1 |
| 3 | 1 |
| 4 | -1 |
| 5 | -5 |
| 6 | -1 |
| 7 | 7 |
| 8 | 13 |
| 9 | -307 |
| 10 | -479 |
| 11 | 1837 |
| 12 | 100921 |
| 13 | 15587 |
| 14 | -23737 |
| 15 | -5729723 |
| 16 | 14731223 |
| 17 | 9129833 |
| 18 | 2722952839 |
| 19 | -4700745901 |
| 20 | -1556262845 |
| 21 | 190717213397 |
| 22 | 24684889339847 |
| 23 | -50242799489 |
| 24 | -148437433077277 |
| 25 | -8592042383621 |
| 26 | 221844330989749 |
| 27 | 176585172615885307 |
| 28 | -9245931549625447 |