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 | -1 |
| 6 | 1 |
| 7 | -1 |
| 8 | -2 |
| 9 | 1 |
| 10 | 1 |
| 11 | -1 |
| 12 | -4 |
| 13 | 0 |
| 14 | -1 |
| 15 | 1 |
| 16 | -1 |
| 17 | -8 |
| 18 | -6 |
| 19 | -12 |
| 20 | 41 |
| 21 | 1 |
| 22 | -1 |
| 23 | -16 |
| 24 | -30 |
| 25 | -72 |
| 26 | 180 |
| 27 | -131 |
| 28 | 1 |
| 29 | -1 |
| 30 | -32 |
| 31 | -114 |
| 32 | -360 |
| 33 | 840 |
| 34 | -1080 |
| 35 | 1499 |
| 36 | 1 |
| 37 | -1 |
| 38 | -64 |
| 39 | -390 |
| 40 | -1656 |
| 41 | 4200 |
| 42 | -8640 |
| 43 | 15120 |
| 44 | -4159 |
| 45 | 1 |
| 46 | -1 |
| 47 | -128 |
| 48 | -1266 |
| 49 | -7272 |
| 50 | 22440 |
| 51 | -69120 |
| 52 | 161280 |
| 53 | -45360 |