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 | -1 |
| 2 | 2 |
| 3 | -3 |
| 4 | 3 |
| 5 | 0 |
| 6 | -10 |
| 7 | 35 |
| 8 | -90 |
| 9 | 200 |
| 10 | -400 |
| 11 | 726 |
| 12 | -1188 |
| 13 | 1716 |
| 14 | -2080 |
| 15 | 1820 |
| 16 | -312 |
| 17 | -2704 |
| 18 | 5408 |
| 19 | 455 |
| 20 | -39195 |
| 21 | 170313 |
| 22 | -523029 |
| 23 | 1352078 |
| 24 | -3114774 |
| 25 | 6548074 |
| 26 | -12668578 |
| 27 | 22492886 |
| 28 | -36020998 |
| 29 | 49549110 |
| 30 | -49549110 |
| 31 | 0 |
| 32 | 182029056 |
| 33 | -670853984 |
| 34 | 1809734560 |
| 35 | -4242470755 |