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 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 1 |
| 6 | -5 |
| 7 | 15 |
| 8 | -35 |
| 9 | 71 |
| 10 | -135 |
| 11 | 255 |
| 12 | -495 |
| 13 | 991 |
| 14 | -2015 |
| 15 | 4095 |
| 16 | -8255 |
| 17 | 16511 |
| 18 | -32895 |
| 19 | 65535 |
| 20 | -130815 |
| 21 | 261630 |
| 22 | -523753 |
| 23 | 1048322 |
| 24 | -2096151 |
| 25 | 4183700 |
| 26 | -8324849 |
| 27 | 16480854 |
| 28 | -32363019 |
| 29 | 62784774 |
| 30 | -119759849 |
| 31 | 223346544 |
| 32 | -404491999 |
| 33 | 705032194 |
| 34 | -1166803109 |