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) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | -1 |
| 4 | 1 |
| 5 | -1 |
| 6 | 1 |
| 7 | 1 |
| 8 | -1 |
| 9 | 1 |
| 10 | -5 |
| 11 | 1 |
| 12 | -1 |
| 13 | 5 |
| 14 | -1 |
| 15 | 21 |
| 16 | 1 |
| 17 | -1 |
| 18 | 19 |
| 19 | -61 |
| 20 | 1 |
| 21 | -105 |
| 22 | 1 |
| 23 | -1 |
| 24 | 69 |
| 25 | -1513 |
| 26 | 1385 |
| 27 | -1 |
| 28 | 635 |
| 29 | 1 |
| 30 | -1 |
| 31 | 251 |
| 32 | -33661 |
| 33 | 315523 |
| 34 | -50521 |
| 35 | 1 |
| 36 | -4507 |
| 37 | 1 |
| 38 | -1 |
| 39 | 923 |
| 40 | -750751 |
| 41 | 60376809 |
| 42 | -136085041 |
| 43 | 2702765 |
| 44 | -1 |
| 45 | 36457 |
| 46 | 1 |
| 47 | -1 |
| 48 | 3431 |
| 49 | -17116009 |
| 50 | 11593285251 |