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 | -2 |
| 2 | 1 |
| 3 | 0 |
| 4 | -2 |
| 5 | 1 |
| 6 | 0 |
| 7 | -12 |
| 8 | 4 |
| 9 | 1 |
| 10 | 0 |
| 11 | -144 |
| 12 | 28 |
| 13 | 20 |
| 14 | 1 |
| 15 | 0 |
| 16 | -2880 |
| 17 | 216 |
| 18 | 508 |
| 19 | 50 |
| 20 | 1 |
| 21 | 0 |
| 22 | -86400 |
| 23 | -2592 |
| 24 | 17400 |
| 25 | 2548 |
| 26 | 98 |
| 27 | 1 |
| 28 | 0 |
| 29 | -3628800 |
| 30 | -449280 |
| 31 | 788688 |
| 32 | 153760 |
| 33 | 8568 |
| 34 | 168 |
| 35 | 1 |
| 36 | 0 |
| 37 | -203212800 |
| 38 | -42405120 |
| 39 | 46032768 |
| 40 | 11269008 |
| 41 | 811648 |
| 42 | 23016 |
| 43 | 264 |
| 44 | 1 |
| 45 | 0 |
| 46 | -14631321600 |
| 47 | -4187635200 |
| 48 | 3372731136 |