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 | 0 |
| 3 | -4 |
| 4 | -6 |
| 5 | 28 |
| 6 | 119 |
| 7 | -116 |
| 8 | -1820 |
| 9 | -2128 |
| 10 | 22212 |
| 11 | 79877 |
| 12 | -172700 |
| 13 | -1652728 |
| 14 | -857428 |
| 15 | 25387284 |
| 16 | 71506309 |
| 17 | -268817888 |
| 18 | -1838702048 |
| 19 | 449975584 |
| 20 | 33164610276 |
| 21 | 68575577309 |
| 22 | -429542625096 |
| 23 | -2221814345660 |
| 24 | 2539462697398 |
| 25 | 46048818685880 |
| 26 | 61721413191310 |