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 | 9 |
| 4 | 30 |
| 5 | 96 |
| 6 | 309 |
| 7 | 996 |
| 8 | 3207 |
| 9 | 10329 |
| 10 | 33267 |
| 11 | 107142 |
| 12 | 345072 |
| 13 | 1111371 |
| 14 | 3579384 |
| 15 | 11528097 |
| 16 | 37128459 |
| 17 | 119579361 |
| 18 | 385128390 |
| 19 | 1240380240 |
| 20 | 3994883733 |