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 | -2 |
| 4 | 4 |
| 5 | -8 |
| 6 | 15 |
| 7 | -25 |
| 8 | 35 |
| 9 | -35 |
| 10 | 0 |
| 11 | 126 |
| 12 | -462 |
| 13 | 1253 |
| 14 | -2989 |
| 15 | 6615 |
| 16 | -13867 |
| 17 | 27734 |
| 18 | -52921 |
| 19 | 95863 |
| 20 | -163115 |
| 21 | 255493 |
| 22 | -352716 |
| 23 | 379050 |
| 24 | -134596 |
| 25 | -828875 |
| 26 | 3407821 |
| 27 | -9217717 |
| 28 | 20837509 |
| 29 | -41675018 |
| 30 | 74480265 |
| 31 | -116145145 |
| 32 | 143502875 |
| 33 | -78990635 |
| 34 | -286097760 |
| 35 | 1453179125 |