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) |
|---|---|
| 1 | 1 |
| 2 | -744 |
| 3 | 356652 |
| 4 | -140361152 |
| 5 | 49336682190 |
| 6 | -16114625669088 |
| 7 | 4999042477430456 |
| 8 | -1492669384085015040 |
| 9 | 432762759484818142437 |
| 10 | -122566701136436206749360 |
| 11 | 34058364214245581228710692 |
| 12 | -9315629487329800685570383104 |
| 13 | 2514284824201628853303708453062 |