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 | 4 |
| 3 | 4 |
| 4 | -13 |
| 5 | -81 |
| 6 | -389 |
| 7 | -198 |
| 8 | 7455 |
| 9 | 44515 |
| 10 | 198661 |
| 11 | 70243 |
| 12 | -5428624 |
| 13 | -40239313 |
| 14 | -218619844 |
| 15 | -408542577 |
| 16 | 3648305171 |
| 17 | 44441073999 |
| 18 | 339489511573 |
| 19 | 1430556904456 |
| 20 | 2122222427956 |
| 21 | -35048613488679 |
| 22 | -504238969376070 |
| 23 | -3684488832562182 |
| 24 | -21342732340391295 |
| 25 | -67688326964892247 |