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 | 1 |
| 3 | 2 |
| 4 | 7 |
| 5 | 28 |
| 6 | 124 |
| 7 | 588 |
| 8 | 2939 |
| 9 | 15292 |
| 10 | 82168 |
| 11 | 453376 |
| 12 | 2558074 |
| 13 | 14712038 |
| 14 | 86029132 |
| 15 | 510455002 |
| 16 | 3068304865 |
| 17 | 18658787150 |
| 18 | 114663168405 |
| 19 | 711391109162 |
| 20 | 4452321247688 |
| 21 | 28090360338572 |
| 22 | 178550339417087 |
| 23 | 1142799275636690 |