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 | -3 |
| 4 | -7 |
| 5 | 5 |
| 6 | 33 |
| 7 | 269 |
| 8 | 393 |
| 9 | -1451 |
| 10 | -4815 |
| 11 | -14115 |
| 12 | -2791 |
| 13 | 171685 |
| 14 | 398145 |
| 15 | -3887699 |
| 16 | -10399319 |
| 17 | 6567925 |
| 18 | 63031889 |
| 19 | 558518141 |
| 20 | 853157689 |
| 21 | -4400392635 |
| 22 | -14954126751 |
| 23 | 29904043597 |
| 24 | 151457170889 |
| 25 | 344861133205 |
| 26 | 170895616881 |
| 27 | -12627954103779 |
| 28 | -30049168949927 |