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 | -4 |
| 3 | 4 |
| 4 | -13 |
| 5 | 16 |
| 6 | -43 |
| 7 | 61 |
| 8 | -145 |
| 9 | 226 |
| 10 | -496 |
| 11 | 823 |
| 12 | -1714 |
| 13 | 2965 |
| 14 | -5965 |
| 15 | 10609 |
| 16 | -20860 |
| 17 | 37792 |
| 18 | -73189 |
| 19 | 134236 |
| 20 | -257359 |
| 21 | 475897 |
| 22 | -906313 |
| 23 | 1685050 |
| 24 | -3194836 |
| 25 | 5961463 |
| 26 | -11269558 |
| 27 | 21079225 |
| 28 | -39770137 |
| 29 | 74507233 |
| 30 | -140389636 |
| 31 | 263291836 |
| 32 | -495676141 |
| 33 | 930265144 |