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 | -3 |
| 5 | 6 |
| 6 | -9 |
| 7 | 17 |
| 8 | -27 |
| 9 | 48 |
| 10 | -80 |
| 11 | 139 |
| 12 | -233 |
| 13 | 402 |
| 14 | -680 |
| 15 | 1165 |
| 16 | -1979 |
| 17 | 3382 |
| 18 | -5754 |
| 19 | 9822 |
| 20 | -16727 |
| 21 | 28531 |
| 22 | -48613 |
| 23 | 82893 |
| 24 | -141268 |
| 25 | 240847 |
| 26 | -410505 |
| 27 | 699808 |
| 28 | -1192838 |
| 29 | 2033410 |
| 30 | -3466085 |
| 31 | 5908459 |
| 32 | -10071512 |
| 33 | 17168221 |
| 34 | -29265017 |
| 35 | 49885842 |
| 36 | -85035890 |
| 37 | 144953845 |
| 38 | -247090156 |
| 39 | 421194210 |