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 | 1 |
| 2 | 3 |
| 3 | 10 |
| 4 | 29 |
| 5 | 81 |
| 6 | 220 |
| 7 | 589 |
| 8 | 1563 |
| 9 | 4126 |
| 10 | 10857 |
| 11 | 28513 |
| 12 | 74792 |
| 13 | 196041 |
| 14 | 513619 |
| 15 | 1345282 |
| 16 | 3522981 |
| 17 | 9224881 |
| 18 | 24153636 |
| 19 | 63239221 |
| 20 | 165569195 |
| 21 | 433476726 |
| 22 | 1134874513 |
| 23 | 2971168705 |
| 24 | 7778667024 |
| 25 | 20364889681 |
| 26 | 53316094755 |
| 27 | 139583544634 |