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 | -3 |
| 2 | 1 |
| 3 | -2 |
| 4 | 4 |
| 5 | -8 |
| 6 | 16 |
| 7 | -32 |
| 8 | 64 |
| 9 | -128 |
| 10 | 256 |
| 11 | -511 |
| 12 | 1012 |
| 13 | -1969 |
| 14 | 3718 |
| 15 | -6721 |
| 16 | 11440 |
| 17 | -17875 |
| 18 | 24310 |
| 19 | -24310 |
| 20 | 1 |
| 21 | 92357 |
| 22 | -352484 |
| 23 | 997568 |
| 24 | -2485241 |
| 25 | 5754023 |
| 26 | -12680954 |
| 27 | 26924183 |
| 28 | -55410641 |
| 29 | 110821282 |
| 30 | -215426354 |
| 31 | 406270424 |
| 32 | -740354803 |
| 33 | 1294617071 |
| 34 | -2145852302 |