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 | 0 |
| 3 | 0 |
| 4 | -4 |
| 5 | 4 |
| 6 | 0 |
| 7 | 0 |
| 8 | 6 |
| 9 | -15 |
| 10 | 9 |
| 11 | 0 |
| 12 | -4 |
| 13 | 40 |
| 14 | -36 |
| 15 | 0 |
| 16 | -15 |
| 17 | -39 |
| 18 | 90 |
| 19 | -36 |
| 20 | 64 |
| 21 | -28 |
| 22 | -180 |
| 23 | 144 |
| 24 | -96 |
| 25 | 206 |
| 26 | 106 |
| 27 | -300 |
| 28 | 148 |
| 29 | -540 |
| 30 | 332 |
| 31 | 480 |
| 32 | -232 |
| 33 | 610 |
| 34 | -1029 |
| 35 | -189 |
| 36 | 114 |
| 37 | -86 |
| 38 | 1880 |
| 39 | -1068 |
| 40 | 24 |
| 41 | -921 |
| 42 | -1545 |
| 43 | 2466 |
| 44 | -300 |
| 45 | 2858 |
| 46 | -1514 |
| 47 | -3180 |
| 48 | 976 |
| 49 | -4121 |
| 50 | 5590 |
| 51 | 1995 |