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 | 0 |
| 3 | -8 |
| 4 | -16 |
| 5 | -64 |
| 6 | -192 |
| 7 | -384 |
| 8 | -1024 |
| 9 | -2560 |
| 10 | -5120 |
| 11 | -12288 |
| 12 | -28672 |
| 13 | -57344 |
| 14 | -131072 |
| 15 | -294912 |
| 16 | -589824 |
| 17 | -1310720 |
| 18 | -2883584 |
| 19 | -5767168 |
| 20 | -12582912 |
| 21 | -27262976 |
| 22 | -54525952 |
| 23 | -117440512 |
| 24 | -251658240 |
| 25 | -503316480 |
| 26 | -1073741824 |
| 27 | -2281701376 |