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 | 0 |
| 1 | -1 |
| 2 | 7 |
| 3 | -118 |
| 4 | 2079 |
| 5 | -37225 |
| 6 | 667744 |
| 7 | -11981593 |
| 8 | 214999407 |
| 9 | -3858003766 |
| 10 | 69229057975 |
| 11 | -1242265012561 |
| 12 | 22291541096832 |
| 13 | -400005474543793 |
| 14 | 7177807000202839 |
| 15 | -128800520527828150 |
| 16 | 2311231562497354959 |
| 17 | -41473367604415793593 |
| 18 | 744209385316963976032 |
| 19 | -13354295568100875681481 |