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 | 2 |
| 2 | 4 |
| 3 | 12 |
| 4 | 36 |
| 5 | 106 |
| 6 | 249 |
| 7 | 613 |
| 8 | 1732 |
| 9 | 8028 |
| 10 | 23348 |
| 11 | 69370 |
| 12 | 210807 |
| 13 | 634839 |
| 14 | 1893582 |
| 15 | 5686389 |
| 16 | 17031777 |
| 17 | 51073675 |
| 18 | 153185957 |
| 19 | 459516225 |
| 20 | 1378707224 |
| 21 | 4135278456 |