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 | 0 |
| 2 | -1 |
| 3 | 3 |
| 4 | -6 |
| 5 | 6 |
| 6 | 15 |
| 7 | -107 |
| 8 | 349 |
| 9 | -672 |
| 10 | 39 |
| 11 | 5835 |
| 12 | -27654 |
| 13 | 75765 |
| 14 | -95799 |
| 15 | -279129 |
| 16 | 2297970 |
| 17 | -8377854 |
| 18 | 17663640 |
| 19 | -996624 |
| 20 | -177445221 |
| 21 | 888491025 |
| 22 | -2551959604 |
| 23 | 3337931168 |
| 24 | 10407149226 |
| 25 | -87719805853 |
| 26 | 328682535695 |
| 27 | -708428979213 |
| 28 | 15252552804 |
| 29 | 7616368090377 |
| 30 | -38693979668535 |