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 | 0 |
| 2 | 1 |
| 3 | -3 |
| 4 | 1 |
| 5 | -6 |
| 6 | 10 |
| 7 | -9 |
| 8 | 28 |
| 9 | -39 |
| 10 | 55 |
| 11 | -123 |
| 12 | 172 |
| 13 | -288 |
| 14 | 541 |
| 15 | -804 |
| 16 | 1405 |
| 17 | -2427 |
| 18 | 3817 |
| 19 | -6642 |
| 20 | 11098 |
| 21 | -18093 |
| 22 | 31024 |
| 23 | -51387 |
| 24 | 85303 |
| 25 | -144459 |
| 26 | 239464 |
| 27 | -400368 |
| 28 | 672841 |
| 29 | -1118760 |
| 30 | 1873945 |
| 31 | -3137283 |
| 32 | 5230225 |
| 33 | -8759118 |
| 34 | 14642074 |
| 35 | -24449793 |
| 36 | 40919428 |
| 37 | -68376015 |
| 38 | 114268807 |
| 39 | -191134299 |
| 40 | 319396852 |