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 | -2 |
| 2 | 1 |
| 3 | -2 |
| 4 | 4 |
| 5 | -8 |
| 6 | 16 |
| 7 | -31 |
| 8 | 56 |
| 9 | -91 |
| 10 | 126 |
| 11 | -126 |
| 12 | 1 |
| 13 | 449 |
| 14 | -1624 |
| 15 | 4249 |
| 16 | -9499 |
| 17 | 18998 |
| 18 | -34356 |
| 19 | 55453 |
| 20 | -75734 |
| 21 | 70889 |
| 22 | 26334 |
| 23 | -379050 |
| 24 | 1352079 |
| 25 | -3713651 |
| 26 | 9000226 |
| 27 | -20136807 |
| 28 | 42409969 |
| 29 | -84819938 |
| 30 | 161567266 |
| 31 | -292710631 |
| 32 | 501416816 |
| 33 | -801992971 |
| 34 | 1167081366 |
| 35 | -1453179126 |