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 | 0 |
| 3 | 1 |
| 4 | 2 |
| 5 | 7 |
| 6 | 14 |
| 7 | 52 |
| 8 | 104 |
| 9 | 333 |
| 10 | 870 |
| 11 | 2571 |
| 12 | 4590 |
| 13 | 20440 |
| 14 | 56736 |
| 15 | 133782 |
| 16 | 327558 |
| 17 | 1265391 |
| 18 | 2612694 |
| 19 | 10188836 |
| 20 | 20769420 |
| 21 | 76562106 |