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 | 21 |
| 2 | 108 |
| 3 | 440 |
| 4 | 1690 |
| 5 | 6405 |
| 6 | 24276 |
| 7 | 92340 |
| 8 | 352674 |
| 9 | 1352032 |