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 | 4 |
| 4 | 1 |
| 5 | -1 |
| 6 | 36 |
| 7 | 17 |
| 8 | -21 |
| 9 | 4 |
| 10 | 576 |
| 11 | 362 |
| 12 | -501 |
| 13 | 154 |
| 14 | -15 |
| 15 | 14400 |
| 16 | 10394 |
| 17 | -15325 |
| 18 | 5810 |
| 19 | -935 |
| 20 | 56 |
| 21 | 518400 |
| 22 | 396384 |
| 23 | -602390 |
| 24 | 250785 |
| 25 | -49385 |
| 26 | 4791 |
| 27 | -185 |
| 28 | 25401600 |
| 29 | 19569696 |
| 30 | -29876966 |
| 31 | 12619761 |
| 32 | -2569805 |
| 33 | 270459 |
| 34 | -13349 |
| 35 | 204 |
| 36 | 1625702400 |
| 37 | 1221167184 |
| 38 | -1830986612 |
| 39 | 726128116 |
| 40 | -122438799 |
| 41 | 5139736 |
| 42 | 1144962 |