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 | -7 |
| 2 | 38 |
| 3 | -232 |
| 4 | 1928 |
| 5 | -16672 |
| 6 | 133508 |
| 7 | -1044736 |
| 8 | 8337920 |
| 9 | -67162624 |
| 10 | 537953708 |
| 11 | -4294193152 |
| 12 | 34336008272 |
| 13 | -274889261056 |
| 14 | 2199555817952 |
| 15 | -17592017354752 |
| 16 | 140725278645248 |
| 17 | -1125902437187584 |
| 18 | 9007484455265852 |
| 19 | -72057555801604096 |
| 20 | 576453982622834768 |
| 21 | -4611686599619510272 |
| 22 | 36893651043755447672 |
| 23 | -295147896302964047872 |