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 | 32 |
| 6 | -80 |
| 7 | 192 |
| 8 | -448 |
| 9 | 1024 |
| 10 | -2304 |
| 11 | 5120 |
| 12 | -11264 |
| 13 | 24576 |
| 14 | -53248 |
| 15 | 114688 |
| 16 | -245760 |
| 17 | 524288 |
| 18 | -1114112 |
| 19 | 2359296 |
| 20 | -4980736 |
| 21 | 10485760 |
| 22 | -22020096 |
| 23 | 46137344 |
| 24 | -96468992 |
| 25 | 201326592 |
| 26 | -419430400 |
| 27 | 872415232 |
| 28 | -1811939328 |
| 29 | 3758096384 |
| 30 | -7784628224 |
| 31 | 16106127360 |