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 | -2 |
| 2 | -1 |
| 3 | -4 |
| 4 | -19 |
| 5 | -110 |
| 6 | -745 |
| 7 | -5752 |
| 8 | -49775 |
| 9 | -476994 |
| 10 | -5016069 |
| 11 | -57462828 |
| 12 | -712732987 |
| 13 | -9521244982 |
| 14 | -136356161873 |
| 15 | -2084860795232 |
| 16 | -33907076207495 |
| 17 | -584602069590058 |
| 18 | -10652917092110429 |
| 19 | -204604743619641620 |
| 20 | -4131502481607654739 |
| 21 | -87507494737954740126 |