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 | -2 |
| 3 | -2 |
| 4 | -4 |
| 5 | -8 |
| 6 | -18 |
| 7 | -42 |
| 8 | -102 |
| 9 | -254 |
| 10 | -646 |
| 11 | -1670 |
| 12 | -4376 |
| 13 | -11596 |
| 14 | -31022 |
| 15 | -83670 |
| 16 | -227268 |
| 17 | -621144 |
| 18 | -1706934 |
| 19 | -4713558 |
| 20 | -13072764 |
| 21 | -36398568 |
| 22 | -101704038 |
| 23 | -285095118 |
| 24 | -801526446 |
| 25 | -2259520830 |
| 26 | -6385455594 |
| 27 | -18086805002 |
| 28 | -51339636952 |
| 29 | -146015545604 |