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 | 0 |
| 1 | 1 |
| 2 | -6 |
| 3 | 116 |
| 4 | -4816 |
| 5 | 342736 |
| 6 | -37272576 |
| 7 | 5748462656 |
| 8 | -1193465153536 |
| 9 | 320935235205376 |
| 10 | -108513125117853696 |
| 11 | 45057835625375568896 |
| 12 | -22540295648947188269056 |
| 13 | 13370560809273727964041216 |