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 | -2 |
| 3 | -5 |
| 4 | -17 |
| 5 | -64 |
| 6 | -259 |
| 7 | -1098 |
| 8 | -4815 |
| 9 | -21659 |
| 10 | -99385 |
| 11 | -463385 |
| 12 | -2189070 |
| 13 | -10455340 |
| 14 | -50402858 |
| 15 | -244929608 |
| 16 | -1198504743 |
| 17 | -5900360016 |
| 18 | -29204546125 |
| 19 | -145244328630 |
| 20 | -725451444795 |
| 21 | -3637422742470 |
| 22 | -18301949731665 |
| 23 | -92380935149100 |
| 24 | -467659449093330 |