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 | -1 |
| 4 | 0 |
| 5 | 3 |
| 6 | -9 |
| 7 | 19 |
| 8 | -35 |
| 9 | 63 |
| 10 | -119 |
| 11 | 239 |
| 12 | -495 |
| 13 | 1023 |
| 14 | -2079 |
| 15 | 4158 |
| 16 | -8239 |
| 17 | 16247 |
| 18 | -31823 |
| 19 | 61402 |
| 20 | -115291 |
| 21 | 207669 |
| 22 | -352715 |
| 23 | 550429 |
| 24 | -748143 |
| 25 | 748143 |
| 26 | 1 |
| 27 | -2848367 |
| 28 | 10897033 |
| 29 | -30955333 |
| 30 | 77558760 |
| 31 | -181129041 |
| 32 | 404458737 |
| 33 | -875889377 |
| 34 | 1855921144 |
| 35 | -3870685665 |