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 | -3 |
| 2 | 7 |
| 3 | -16 |
| 4 | 36 |
| 5 | -81 |
| 6 | 182 |
| 7 | -409 |
| 8 | 919 |
| 9 | -2065 |
| 10 | 4640 |
| 11 | -10426 |
| 12 | 23427 |
| 13 | -52640 |
| 14 | 118281 |
| 15 | -265775 |
| 16 | 597191 |
| 17 | -1341876 |
| 18 | 3015168 |
| 19 | -6775021 |
| 20 | 15223334 |
| 21 | -34206521 |
| 22 | 76861355 |
| 23 | -172705897 |
| 24 | 388066628 |
| 25 | -871977798 |
| 26 | 1959316327 |
| 27 | -4402543824 |
| 28 | 9892426177 |
| 29 | -22228079851 |
| 30 | 49946042055 |
| 31 | -112227737784 |