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 | 4 |
| 2 | 16 |
| 3 | 52 |
| 4 | 144 |
| 5 | 420 |
| 6 | 816 |
| 7 | 1732 |
| 8 | 3508 |
| 9 | 7060 |
| 10 | 18640 |