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 | 1 |
| 3 | -2 |
| 4 | -1 |
| 5 | 11 |
| 6 | -18 |
| 7 | -41 |
| 8 | 317 |
| 9 | -680 |
| 10 | -1767 |
| 11 | 19911 |
| 12 | -68264 |
| 13 | -59643 |
| 14 | 2076973 |
| 15 | -11905466 |
| 16 | 18577387 |
| 17 | 269836343 |
| 18 | -2819431570 |
| 19 | 12357816867 |
| 20 | 17355428041 |
| 21 | -752675321800 |
| 22 | 6318046208653 |
| 23 | -21416130683133 |
| 24 | -152569023028272 |
| 25 | 3016508107668601 |
| 26 | -23667435182395287 |