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) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 0 |
| 3 | 4 |
| 4 | -4 |
| 5 | 11 |
| 6 | -13 |
| 7 | 39 |
| 8 | -73 |
| 9 | 144 |
| 10 | -256 |
| 11 | 559 |
| 12 | -1116 |
| 13 | 2188 |
| 14 | -4317 |
| 15 | 8804 |
| 16 | -17591 |
| 17 | 34992 |
| 18 | -69815 |
| 19 | 140097 |
| 20 | -280416 |
| 21 | 560077 |
| 22 | -1119327 |
| 23 | 2240719 |
| 24 | -4482527 |
| 25 | 8961129 |
| 26 | -17920037 |
| 27 | 35847885 |
| 28 | -71699202 |
| 29 | 143384383 |
| 30 | -286760131 |
| 31 | 573549105 |
| 32 | -1147115913 |
| 33 | 2294173485 |
| 34 | -4588309651 |
| 35 | 9176739373 |