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 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 3 |
| 4 | 14 |
| 5 | 50 |
| 6 | 195 |
| 7 | 721 |
| 8 | 2716 |
| 9 | 10116 |
| 10 | 37845 |
| 11 | 141295 |
| 12 | 528330 |
| 13 | 1975766 |
| 14 | 7395479 |
| 15 | 27698685 |
| 16 | 103821240 |
| 17 | 389410568 |
| 18 | 1461605481 |
| 19 | 5489516955 |
| 20 | 20630539910 |
| 21 | 77579118330 |
| 22 | 291893775019 |
| 23 | 1098848179561 |
| 24 | 4138773239892 |
| 25 | 15596070165900 |
| 26 | 58797332264125 |
| 27 | 221762856917511 |
| 28 | 836756771788098 |