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 | 1 |
| 3 | -1 |
| 4 | 1 |
| 5 | -3 |
| 6 | 1 |
| 7 | -1 |
| 8 | 25 |
| 9 | -1 |
| 10 | 1 |
| 11 | -49 |
| 12 | 1 |
| 13 | -1 |
| 14 | 9 |
| 15 | -3 |
| 16 | 1 |
| 17 | -363 |
| 18 | 3025 |
| 19 | -1 |
| 20 | 169 |
| 21 | -169 |
| 22 | 1 |
| 23 | -3 |
| 24 | 1 |
| 25 | -49 |
| 26 | 289 |
| 27 | -289 |
| 28 | 7225 |
| 29 | -361 |
| 30 | 361 |
| 31 | -361 |
| 32 | 1 |
| 33 | -1 |
| 34 | 1 |
| 35 | -529 |
| 36 | 529 |
| 37 | -529 |
| 38 | 330625 |
| 39 | -148225 |
| 40 | 3025 |
| 41 | -675 |
| 42 | 9 |
| 43 | -3 |
| 44 | 7569 |
| 45 | -2523 |
| 46 | 142129 |
| 47 | -409757907 |
| 48 | 808201 |
| 49 | -961 |
| 50 | 8649 |
| 51 | -2883 |
| 52 | 1 |
| 53 | -147 |