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 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 17 |
| 4 | 85 |
| 5 | 459 |
| 6 | 2614 |
| 7 | 15454 |
| 8 | 93947 |
| 9 | 583568 |
| 10 | 3687761 |
| 11 | 23633072 |
| 12 | 153227250 |
| 13 | 1003281314 |
| 14 | 6624658716 |
| 15 | 44062205158 |
| 16 | 294938814921 |
| 17 | 1985330061570 |
| 18 | 13430612284606 |
| 19 | 91262392343333 |
| 20 | 622624395706714 |
| 21 | 4263163419492661 |