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 | -19 |
| 6 | 79 |
| 7 | 11 |
| 8 | -2339 |
| 9 | -11813 |
| 10 | 677 |
| 11 | 2117 |
| 12 | -308963 |
| 13 | -64604977 |
| 14 | 131301607 |
| 15 | 263101079 |
| 16 | -5614643 |
| 17 | -1768132943 |
| 18 | 46949081169401 |
| 19 | 9606907803497 |
| 20 | -10635113572583999 |
| 21 | -158812278992229461 |
| 22 | 8131167478793551 |
| 23 | 9112944418860287 |
| 24 | -40395223967437706149 |