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 | -15 |
| 3 | -71 |
| 4 | -255 |
| 5 | -799 |
| 6 | -2303 |
| 7 | -6271 |
| 8 | -16383 |
| 9 | -41471 |
| 10 | -102399 |
| 11 | -247807 |
| 12 | -589823 |
| 13 | -1384447 |
| 14 | -3211263 |
| 15 | -7372799 |
| 16 | -16777215 |
| 17 | -37879807 |
| 18 | -84934655 |
| 19 | -189267967 |
| 20 | -419430399 |
| 21 | -924844031 |
| 22 | -2030043135 |
| 23 | -4437573631 |
| 24 | -9663676415 |
| 25 | -20971519999 |
| 26 | -45365592063 |