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 | -2 |
| 2 | 0 |
| 3 | 2 |
| 4 | 2 |
| 5 | -6 |
| 6 | -2 |
| 7 | 10 |
| 8 | 6 |
| 9 | -22 |
| 10 | -10 |
| 11 | 42 |
| 12 | 22 |
| 13 | -86 |
| 14 | -42 |
| 15 | 170 |
| 16 | 86 |
| 17 | -342 |
| 18 | -170 |
| 19 | 682 |
| 20 | 342 |
| 21 | -1366 |
| 22 | -682 |
| 23 | 2730 |
| 24 | 1366 |
| 25 | -5462 |
| 26 | -2730 |
| 27 | 10922 |
| 28 | 5462 |
| 29 | -21846 |
| 30 | -10922 |
| 31 | 43690 |
| 32 | 21846 |
| 33 | -87382 |
| 34 | -43690 |
| 35 | 174762 |
| 36 | 87382 |
| 37 | -349526 |
| 38 | -174762 |
| 39 | 699050 |
| 40 | 349526 |
| 41 | -1398102 |
| 42 | -699050 |
| 43 | 2796202 |
| 44 | 1398102 |
| 45 | -5592406 |
| 46 | -2796202 |