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 | 0 |
| 3 | -3 |
| 4 | -6 |
| 5 | 15 |
| 6 | 75 |
| 7 | 84 |
| 8 | -1820 |
| 9 | -123 |
| 10 | -10725 |
| 11 | 475816 |
| 12 | -3554562 |
| 13 | 32763107 |
| 14 | -501958275 |
| 15 | 6877337128 |
| 16 | -95130710792 |
| 17 | 1486984480729 |
| 18 | -24736452203529 |
| 19 | 430314112493264 |
| 20 | -7930867848273070 |
| 21 | 154362838472661367 |
| 22 | -3154456665148212743 |