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 | 67 |
| 4 | -283 |
| 5 | -5911 |
| 6 | 269891 |
| 7 | 114551 |
| 8 | -9390523 |
| 9 | -1021798901 |
| 10 | 273468378049 |
| 11 | 3918564638257 |
| 12 | -872697935308349 |
| 13 | -131115162268691 |
| 14 | 1397912875942181 |
| 15 | 2172284899403876321 |
| 16 | -3926446823184958835813 |
| 17 | -284746035618826337921 |
| 18 | 286113629384558337084185927 |