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 | 16 |
| 7 | -32 |
| 8 | 64 |
| 9 | -127 |
| 10 | 246 |
| 11 | -456 |
| 12 | 792 |
| 13 | -1254 |
| 14 | 1716 |
| 15 | -1716 |
| 16 | 1 |
| 17 | 6418 |
| 18 | -24156 |
| 19 | 67080 |
| 20 | -162924 |
| 21 | 364608 |
| 22 | -767976 |
| 23 | 1535953 |
| 24 | -2922702 |
| 25 | 5273624 |
| 26 | -8934120 |
| 27 | 13904190 |
| 28 | -18874260 |
| 29 | 18874260 |
| 30 | 1 |
| 31 | -71705866 |
| 32 | 272491892 |
| 33 | -763189064 |
| 34 | 1865459352 |
| 35 | -4190875872 |