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 | 7 |
| 4 | 21 |
| 5 | 61 |
| 6 | 179 |
| 7 | 535 |
| 8 | 1597 |
| 9 | 4781 |
| 10 | 14331 |
| 11 | 42967 |
| 12 | 128869 |
| 13 | 386557 |
| 14 | 1159587 |
| 15 | 3478647 |
| 16 | 10435757 |
| 17 | 31306989 |
| 18 | 93920555 |
| 19 | 281761015 |
| 20 | 845282069 |
| 21 | 2535844733 |
| 22 | 7607531923 |
| 23 | 22822592343 |
| 24 | 68467771805 |
| 25 | 205403307437 |
| 26 | 616209910235 |
| 27 | 1848629712279 |
| 28 | 5545889108805 |