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 | 0 |
| 2 | 1 |
| 3 | -1 |
| 4 | 0 |
| 5 | 3 |
| 6 | -9 |
| 7 | 18 |
| 8 | -27 |
| 9 | 27 |
| 10 | 1 |
| 11 | -92 |
| 12 | 309 |
| 13 | -771 |
| 14 | 1716 |
| 15 | -3627 |
| 16 | 7449 |
| 17 | -14897 |
| 18 | 28764 |
| 19 | -52921 |
| 20 | 91239 |
| 21 | -143718 |
| 22 | 196197 |
| 23 | -196197 |
| 24 | 0 |
| 25 | 737817 |
| 26 | -2785484 |
| 27 | 7758154 |
| 28 | -18894735 |
| 29 | 42409968 |
| 30 | -89718894 |
| 31 | 180879813 |
| 32 | -349599492 |
| 33 | 650139687 |
| 34 | -1166803109 |
| 35 | 2028578278 |