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 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 0 |
| 7 | -1 |
| 8 | 1 |
| 9 | 0 |
| 10 | 0 |
| 11 | 0 |
| 12 | 0 |
| 13 | 0 |
| 14 | 0 |
| 15 | 0 |
| 16 | 1 |
| 17 | 1 |
| 18 | -1 |
| 19 | -9 |
| 20 | 81 |
| 21 | 9 |
| 22 | -1225 |
| 23 | -2500 |
| 24 | 2500 |
| 25 | 2500 |
| 26 | -225 |
| 27 | -121 |
| 28 | 841 |
| 29 | 19044 |
| 30 | -29584 |
| 31 | -355216 |
| 32 | 1527696 |
| 33 | 141376 |
| 34 | -40000 |
| 35 | -40000 |
| 36 | 10000 |
| 37 | 59536 |
| 38 | -258064 |
| 39 | -139876 |
| 40 | 935089 |
| 41 | 885481 |
| 42 | -16384 |
| 43 | -1876900 |
| 44 | 1710864 |
| 45 | 818875456 |
| 46 | -22896531856 |
| 47 | -23799232900 |
| 48 | 66328911936 |
| 49 | 158281561 |
| 50 | -45320023225 |