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 | 0 |
| 4 | 0 |
| 5 | -2 |
| 6 | 4 |
| 7 | -2 |
| 8 | 4 |
| 9 | -6 |
| 10 | 12 |
| 11 | -10 |
| 12 | 20 |
| 13 | -22 |
| 14 | 44 |
| 15 | -42 |
| 16 | 84 |
| 17 | -86 |
| 18 | 172 |
| 19 | -170 |
| 20 | 340 |
| 21 | -342 |
| 22 | 684 |
| 23 | -682 |
| 24 | 1364 |
| 25 | -1366 |
| 26 | 2732 |
| 27 | -2730 |
| 28 | 5460 |
| 29 | -5462 |
| 30 | 10924 |
| 31 | -10922 |
| 32 | 21844 |
| 33 | -21846 |
| 34 | 43692 |
| 35 | -43690 |
| 36 | 87380 |
| 37 | -87382 |
| 38 | 174764 |
| 39 | -174762 |
| 40 | 349524 |
| 41 | -349526 |
| 42 | 699052 |
| 43 | -699050 |
| 44 | 1398100 |
| 45 | -1398102 |