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) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | -3 |
| 4 | 21 |
| 5 | -185 |
| 6 | 2010 |
| 7 | -25914 |
| 8 | 386407 |
| 9 | -6539679 |
| 10 | 123823305 |
| 11 | -2593076255 |
| 12 | 59505341676 |
| 13 | -1484818160748 |
| 14 | 40025880386401 |
| 15 | -1159156815431055 |
| 16 | 35891098374564105 |
| 17 | -1183172853341759129 |
| 18 | 41372997479943753582 |
| 19 | -1529550505546305534414 |
| 20 | 59608871544962952539335 |