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 | 0 |
| 1 | 1 |
| 2 | 1 |
| 3 | 0 |
| 4 | -1 |
| 5 | -1 |
| 6 | 0 |
| 7 | -21 |
| 8 | -21 |
| 9 | 0 |
| 10 | 21 |
| 11 | 21 |
| 12 | 0 |
| 13 | -903 |
| 14 | -903 |
| 15 | 0 |
| 16 | 903 |
| 17 | 903 |
| 18 | 0 |
| 19 | -38829 |
| 20 | -38829 |
| 21 | 0 |
| 22 | 38829 |
| 23 | 38829 |
| 24 | 0 |
| 25 | -1669647 |
| 26 | -1669647 |
| 27 | 0 |
| 28 | 1669647 |
| 29 | 1669647 |
| 30 | 0 |
| 31 | -71794821 |
| 32 | -71794821 |
| 33 | 0 |
| 34 | 71794821 |
| 35 | 71794821 |
| 36 | 0 |
| 37 | -3087177303 |
| 38 | -3087177303 |
| 39 | 0 |
| 40 | 3087177303 |
| 41 | 3087177303 |
| 42 | 0 |