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 | 0 |
| 2 | 2 |
| 3 | 4 |
| 4 | 12 |
| 5 | 52 |
| 6 | 212 |
| 7 | 852 |
| 8 | 3412 |
| 9 | 13652 |
| 10 | 54612 |
| 11 | 218452 |
| 12 | 873812 |
| 13 | 3495252 |
| 14 | 13981012 |
| 15 | 55924052 |
| 16 | 223696212 |