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 | 13 |
| 3 | -301 |
| 4 | 11705 |
| 5 | -698521 |
| 6 | 59340997 |
| 7 | -6782462597 |
| 8 | 1000434618609 |
| 9 | -184576848771889 |
| 10 | 41577074746699261 |
| 11 | -11216502744649033437 |
| 12 | 3567416307426404300713 |
| 13 | -1320192785381894987925961 |
| 14 | 562163981454375064332029365 |
| 15 | -272809563505907130928868599861 |