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 | 5 |
| 2 | -3 |
| 3 | 13 |
| 4 | -19 |
| 5 | 45 |
| 6 | -83 |
| 7 | 173 |
| 8 | -339 |
| 9 | 685 |
| 10 | -1363 |
| 11 | 2733 |
| 12 | -5459 |
| 13 | 10925 |
| 14 | -21843 |
| 15 | 43693 |
| 16 | -87379 |
| 17 | 174765 |
| 18 | -349523 |
| 19 | 699053 |
| 20 | -1398099 |
| 21 | 2796205 |
| 22 | -5592403 |
| 23 | 11184813 |
| 24 | -22369619 |
| 25 | 44739245 |
| 26 | -89478483 |
| 27 | 178956973 |
| 28 | -357913939 |
| 29 | 715827885 |
| 30 | -1431655763 |
| 31 | 2863311533 |
| 32 | -5726623059 |