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 | -7 |
| 4 | -77 |
| 5 | -1145 |
| 6 | -21410 |
| 7 | -481683 |
| 8 | -12655196 |
| 9 | -379998938 |
| 10 | -12830421321 |
| 11 | -480984691304 |
| 12 | -19816691903510 |
| 13 | -889846823832596 |
| 14 | -43247136243424267 |
| 15 | -2261480610502143020 |
| 16 | -126596066994553497948 |
| 17 | -7553154370244179931495 |
| 18 | -478456478496821309024061 |