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 | 4 |
| 2 | -17 |
| 3 | 17 |
| 4 | 72 |
| 5 | -305 |
| 6 | 305 |
| 7 | 1292 |
| 8 | -5473 |
| 9 | 5473 |
| 10 | 23184 |
| 11 | -98209 |
| 12 | 98209 |
| 13 | 416020 |
| 14 | -1762289 |
| 15 | 1762289 |
| 16 | 7465176 |
| 17 | -31622993 |
| 18 | 31622993 |
| 19 | 133957148 |
| 20 | -567451585 |
| 21 | 567451585 |
| 22 | 2403763488 |
| 23 | -10182505537 |
| 24 | 10182505537 |
| 25 | 43133785636 |
| 26 | -182717648081 |
| 27 | 182717648081 |
| 28 | 774004377960 |