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 | -5 |
| 3 | -17 |
| 4 | 73 |
| 5 | 481 |
| 6 | -1709 |
| 7 | -19025 |
| 8 | 52753 |
| 9 | 965953 |
| 10 | -1882709 |
| 11 | -59839889 |
| 12 | 64418905 |
| 13 | 4372890913 |
| 14 | -651783677 |
| 15 | -367974620369 |
| 16 | -309314089439 |
| 17 | 35016249465985 |
| 18 | 66566286588763 |
| 19 | -3715188655737617 |
| 20 | -11303745326856599 |
| 21 | 434518893361657441 |
| 22 | 1858790804545588915 |