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 | 0 |
| 7 | 0 |
| 8 | 0 |
| 9 | 0 |
| 10 | 0 |
| 11 | 0 |
| 12 | 1 |
| 13 | 0 |
| 14 | 0 |
| 15 | 0 |
| 16 | 0 |
| 17 | 0 |
| 18 | 0 |
| 19 | 0 |
| 20 | 16 |
| 21 | 25 |
| 22 | -25 |
| 23 | -100 |
| 24 | 1 |
| 25 | 81 |
| 26 | -16 |
| 27 | -36 |
| 28 | 0 |
| 29 | 1764 |
| 30 | -3136 |
| 31 | -196 |
| 32 | 324 |
| 33 | 16 |
| 34 | -225 |
| 35 | -1764 |
| 36 | 1521 |
| 37 | 9 |
| 38 | -3969 |
| 39 | -4356 |
| 40 | 4761 |
| 41 | 9 |
| 42 | -1225 |
| 43 | -19881 |
| 44 | 5041 |
| 45 | 156816 |
| 46 | -312481 |
| 47 | -167281 |
| 48 | 219024 |
| 49 | 3600 |
| 50 | -186624 |
| 51 | -158404 |
| 52 | 5541316 |
| 53 | 3020644 |
| 54 | -19554084 |
| 55 | -1350244 |
| 56 | 198810000 |