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 | 5 |
| 2 | -7 |
| 3 | 29 |
| 4 | -79 |
| 5 | 245 |
| 6 | -727 |
| 7 | 2189 |
| 8 | -6559 |
| 9 | 19685 |
| 10 | -59047 |
| 11 | 177149 |
| 12 | -531439 |
| 13 | 1594325 |
| 14 | -4782967 |
| 15 | 14348909 |
| 16 | -43046719 |
| 17 | 129140165 |
| 18 | -387420487 |
| 19 | 1162261469 |
| 20 | -3486784399 |
| 21 | 10460353205 |
| 22 | -31381059607 |
| 23 | 94143178829 |
| 24 | -282429536479 |
| 25 | 847288609445 |
| 26 | -2541865828327 |
| 27 | 7625597484989 |