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 | -2 |
| 2 | 6 |
| 3 | -15 |
| 4 | 38 |
| 5 | -95 |
| 6 | 237 |
| 7 | -590 |
| 8 | 1468 |
| 9 | -3651 |
| 10 | 9079 |
| 11 | -22575 |
| 12 | 56131 |
| 13 | -139563 |
| 14 | 347004 |
| 15 | -862774 |
| 16 | 2145156 |
| 17 | -5333599 |
| 18 | 13261165 |
| 19 | -32971820 |
| 20 | 81979285 |
| 21 | -203828691 |
| 22 | 506788203 |
| 23 | -1260049698 |
| 24 | 3132916721 |
| 25 | -7789507968 |
| 26 | 19367394583 |
| 27 | -48154000782 |