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 | -4 |
| 2 | -28 |
| 3 | -56 |
| 4 | 32 |
| 5 | 416 |
| 6 | 832 |
| 7 | -256 |
| 8 | -4864 |
| 9 | -9728 |
| 10 | 2048 |
| 11 | 51200 |
| 12 | 102400 |
| 13 | -16384 |
| 14 | -507904 |
| 15 | -1015808 |
| 16 | 131072 |
| 17 | 4849664 |
| 18 | 9699328 |
| 19 | -1048576 |
| 20 | -45088768 |
| 21 | -90177536 |
| 22 | 8388608 |
| 23 | 411041792 |
| 24 | 822083584 |
| 25 | -67108864 |
| 26 | -3690987520 |
| 27 | -7381975040 |