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 | 1 |
| 2 | -2047 |
| 3 | 177148 |
| 4 | -4196351 |
| 5 | 48828126 |
| 6 | -362621956 |
| 7 | 1977326744 |
| 8 | -8594130943 |
| 9 | 31381236757 |
| 10 | -99951173922 |
| 11 | 285311670612 |
| 12 | -743375186948 |
| 13 | 1792160394038 |
| 14 | -4047587844968 |
| 15 | 8649804864648 |
| 16 | -17600780175359 |
| 17 | 34271896307634 |
| 18 | -64237391641579 |
| 19 | 116490258898220 |
| 20 | -204899955368226 |
| 21 | 350279478046112 |