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 | 0 |
| 3 | 1 |
| 4 | 0 |
| 5 | 1 |
| 6 | -1 |
| 7 | 2 |
| 8 | -2 |
| 9 | 4 |
| 10 | -6 |
| 11 | 10 |
| 12 | -16 |
| 13 | 27 |
| 14 | -44 |
| 15 | 75 |
| 16 | -127 |
| 17 | 218 |
| 18 | -375 |
| 19 | 650 |
| 20 | -1130 |
| 21 | 1974 |
| 22 | -3460 |
| 23 | 6086 |
| 24 | -10736 |
| 25 | 18993 |
| 26 | -33685 |
| 27 | 59882 |
| 28 | -106683 |
| 29 | 190446 |
| 30 | -340611 |
| 31 | 610243 |
| 32 | -1095102 |
| 33 | 1968200 |
| 34 | -3542468 |
| 35 | 6384518 |
| 36 | -11521308 |
| 37 | 20815942 |
| 38 | -37651528 |
| 39 | 68176596 |
| 40 | -123574852 |
| 41 | 224204708 |
| 42 | -407153894 |