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 | 15 |
| 3 | -58 |
| 4 | 229 |
| 5 | -924 |
| 6 | 3795 |
| 7 | -15822 |
| 8 | 66801 |
| 9 | -285072 |
| 10 | 1227759 |
| 11 | -5329938 |
| 12 | 23299309 |
| 13 | -102474004 |
| 14 | 453139947 |
| 15 | -2013469718 |
| 16 | 8985382889 |
| 17 | -40255260696 |
| 18 | 180985860071 |
| 19 | -816328679450 |
| 20 | 3692868722661 |
| 21 | -16750809358364 |
| 22 | 76170701553635 |
| 23 | -347166666620958 |
| 24 | 1585669523701729 |