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 | 0 |
| 2 | -4 |
| 3 | -16 |
| 4 | 0 |
| 5 | 1024 |
| 6 | 16384 |
| 7 | 0 |
| 8 | -16777216 |
| 9 | -1073741824 |
| 10 | 0 |
| 11 | 17592186044416 |
| 12 | 4503599627370496 |
| 13 | 0 |
| 14 | -1180591620717411303424 |
| 15 | -1208925819614629174706176 |
| 16 | 0 |
| 17 | 5070602400912917605986812821504 |
| 18 | 20769187434139310514121985316880384 |