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 | 3 |
| 2 | 9 |
| 3 | 27 |
| 4 | 78 |
| 5 | 222 |
| 6 | 622 |
| 7 | 1722 |
| 8 | 4719 |
| 9 | 12821 |
| 10 | 34575 |
| 11 | 92637 |
| 12 | 246788 |
| 13 | 654120 |
| 14 | 1725900 |
| 15 | 4535172 |
| 16 | 11872941 |
| 17 | 30977943 |
| 18 | 80575109 |
| 19 | 208983471 |
| 20 | 540606474 |
| 21 | 1395061474 |
| 22 | 3591893274 |
| 23 | 9228660318 |
| 24 | 23664610747 |
| 25 | 60570324105 |
| 26 | 154763821419 |
| 27 | 394795932561 |