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 | 4 |
| 4 | -12 |
| 5 | -64 |
| 6 | -208 |
| 7 | 1088 |
| 8 | -960 |
| 9 | -8192 |
| 10 | -6400 |
| 11 | 58368 |
| 12 | -27648 |
| 13 | -344064 |
| 14 | -151552 |
| 15 | 1982464 |
| 16 | -638976 |
| 17 | -10485760 |
| 18 | -3211264 |
| 19 | 54788096 |
| 20 | -13369344 |
| 21 | -272629760 |
| 22 | -63963136 |
| 23 | 1346371584 |
| 24 | -264241152 |
| 25 | -6442450944 |
| 26 | -1224736768 |
| 27 | 30668750848 |