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 | 5 |
| 4 | 13 |
| 5 | 35 |
| 6 | 96 |
| 7 | 264 |
| 8 | 719 |
| 9 | 1914 |
| 10 | 4888 |
| 11 | 11583 |
| 12 | 23540 |
| 13 | 29907 |
| 14 | -57120 |
| 15 | -695742 |
| 16 | -3938275 |
| 17 | -18266657 |
| 18 | -76983710 |
| 19 | -306116660 |
| 20 | -1168987469 |
| 21 | -4327878214 |
| 22 | -15617536020 |
| 23 | -55097816085 |
| 24 | -190320077663 |
| 25 | -643865817117 |
| 26 | -2131713980560 |
| 27 | -6893257768141 |