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 | 1 |
| 3 | 1 |
| 4 | -1 |
| 5 | 3 |
| 6 | -5 |
| 7 | 7 |
| 8 | -7 |
| 9 | 3 |
| 10 | 5 |
| 11 | -9 |
| 12 | -17 |
| 13 | 129 |
| 14 | -417 |
| 15 | 977 |
| 16 | -1809 |
| 17 | 2591 |
| 18 | -2317 |
| 19 | -1061 |
| 20 | 10485 |
| 21 | -27983 |
| 22 | 49165 |
| 23 | -51319 |
| 24 | -26861 |
| 25 | 311455 |
| 26 | -1011473 |
| 27 | 2393275 |
| 28 | -4643591 |
| 29 | 7521265 |
| 30 | -9694135 |
| 31 | 7738137 |
| 32 | 4976985 |
| 33 | -38789975 |
| 34 | 106112817 |
| 35 | -215068927 |
| 36 | 354515933 |
| 37 | -464539803 |