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) |
|---|---|
| 1 | 1 |
| 2 | -1 |
| 3 | 1 |
| 4 | -1 |
| 5 | 1 |
| 6 | 0 |
| 7 | -6 |
| 8 | 27 |
| 9 | -83 |
| 10 | 209 |
| 11 | -455 |
| 12 | 845 |
| 13 | -1169 |
| 14 | 272 |
| 15 | 5916 |
| 16 | -29070 |
| 17 | 98040 |
| 18 | -274075 |
| 19 | 660859 |
| 20 | -1351756 |
| 21 | 2110020 |
| 22 | -1186110 |
| 23 | -8227260 |
| 24 | 47128770 |
| 25 | -170898624 |
| 26 | 505121130 |
| 27 | -1281947030 |
| 28 | 2772309230 |
| 29 | -4708067030 |
| 30 | 3936320480 |
| 31 | 13030540120 |
| 32 | -90168747031 |
| 33 | 348836671587 |
| 34 | -1077316101393 |