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 | -32 |
| 2 | 464 |
| 3 | -4032 |
| 4 | 23624 |
| 5 | -102208 |
| 6 | 369152 |
| 7 | -1288640 |
| 8 | 4532900 |
| 9 | -14879712 |
| 10 | 44466784 |
| 11 | -129948864 |
| 12 | 386117312 |
| 13 | -1105967680 |
| 14 | 2987155392 |
| 15 | -7997827968 |
| 16 | 21623750538 |
| 17 | -56758985984 |
| 18 | 143841619760 |
| 19 | -363972575296 |
| 20 | 920811469312 |