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 | -3 |
| 3 | -11 |
| 4 | 1 |
| 5 | 81 |
| 6 | 141 |
| 7 | -363 |
| 8 | -1791 |
| 9 | -479 |
| 10 | 13597 |
| 11 | 29877 |
| 12 | -54911 |
| 13 | -353807 |
| 14 | -223443 |
| 15 | 2539989 |
| 16 | 6806529 |
| 17 | -8302527 |
| 18 | -73999299 |
| 19 | -73313931 |
| 20 | 489731841 |
| 21 | 1584548241 |
| 22 | -1110170163 |
| 23 | -15812965611 |
| 24 | -21391839999 |
| 25 | 94696016481 |