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 | 7 |
| 5 | 3 |
| 6 | -31 |
| 7 | -17 |
| 8 | 127 |
| 9 | 155 |
| 10 | -2555 |
| 11 | -2073 |
| 12 | 1414477 |
| 13 | 38227 |
| 14 | -57337 |
| 15 | -929569 |
| 16 | 118518239 |
| 17 | 28820619 |
| 18 | -5749691557 |
| 19 | -1109652905 |
| 20 | 91546277357 |
| 21 | 51943281731 |
| 22 | -1792042792463 |
| 23 | -2905151042481 |
| 24 | 1982765468311237 |
| 25 | 191329672483963 |
| 26 | -286994504449393 |
| 27 | -14655626154768697 |
| 28 | 3187598676787461083 |
| 29 | 1291885088448017715 |
| 30 | -4625594554880206790555 |