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 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | -2 |
| 4 | 7 |
| 5 | -14 |
| 6 | 38 |
| 7 | -76 |
| 8 | 187 |
| 9 | -374 |
| 10 | 874 |
| 11 | -1748 |
| 12 | 3958 |
| 13 | -7916 |
| 14 | 17548 |
| 15 | -35096 |
| 16 | 76627 |
| 17 | -153254 |
| 18 | 330818 |
| 19 | -661636 |
| 20 | 1415650 |
| 21 | -2831300 |
| 22 | 6015316 |
| 23 | -12030632 |
| 24 | 25413342 |
| 25 | -50826684 |
| 26 | 106853668 |
| 27 | -213707336 |
| 28 | 447472972 |
| 29 | -894945944 |
| 30 | 1867450648 |
| 31 | -3734901296 |
| 32 | 7770342787 |