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 | -19 |
| 2 | 152 |
| 3 | -665 |
| 4 | 1862 |
| 5 | -4864 |
| 6 | 16891 |
| 7 | -53770 |
| 8 | 126654 |
| 9 | -297768 |
| 10 | 874703 |
| 11 | -2302800 |
| 12 | 5022650 |
| 13 | -11816556 |
| 14 | 30449894 |
| 15 | -70624311 |
| 16 | 153691133 |
| 17 | -351589585 |
| 18 | 812477658 |
| 19 | -1798826901 |
| 20 | 3880086254 |
| 21 | -8420178035 |
| 22 | 18486176635 |