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 | 3 |
| 4 | -3 |
| 5 | 1 |
| 6 | 21 |
| 7 | -21 |
| 8 | 7 |
| 9 | -1 |
| 10 | 315 |
| 11 | -315 |
| 12 | 105 |
| 13 | -15 |
| 14 | 1 |
| 15 | 9765 |
| 16 | -9765 |
| 17 | 3255 |
| 18 | -465 |
| 19 | 31 |
| 20 | -1 |
| 21 | 615195 |
| 22 | -615195 |
| 23 | 205065 |
| 24 | -29295 |
| 25 | 1953 |
| 26 | -63 |
| 27 | 1 |
| 28 | 78129765 |
| 29 | -78129765 |
| 30 | 26043255 |
| 31 | -3720465 |
| 32 | 248031 |
| 33 | -8001 |
| 34 | 127 |
| 35 | -1 |
| 36 | 19923090075 |
| 37 | -19923090075 |
| 38 | 6641030025 |
| 39 | -948718575 |
| 40 | 63247905 |
| 41 | -2040255 |
| 42 | 32385 |
| 43 | -255 |
| 44 | 1 |